96 blazer stalls when hot

Ok. As requested I'm starting a new thread. I've seen a lot of people who have had this issue throughout several different forums but no one has ever posted a resolution that I have found.I bought the blazer last September. 4.3l spider injectors had 175k miles when purchased and super clean. Last summer on hot days, and only after driving 15 - 20 miles the engine would start to hesitate on acceleration. The more gas pedal I would give it, thee more it would hesitate and lose power until it eventually stalled completely . I could let it sit, cool down for 30 minutes and it would restart. This happened 4 times last summer on hot days and each day it was back in the shop from where I purchased it. Fuel rail pressure is always good. Leak down test was done on the fuel rail and it held. The only code I would get was an intermittment small evap leak. Fuel filter was replaced. After several revisits to the mechanic he replaced the ICM (supposedly), then we entered the fall season, the weather cooled, and I never had the stalling issue. I did however sporadically get the small evap leak code come up when I was always below a half tank of fuel. I'd fill up and and next diagnostics cycle the SES would go off. Fast forward through the winter, no problems other than sporadic SES WHEN UNDER HALF TANK. motor was replaced 2 weeks ago with a new one. 500 miles on the motor and we had our first 80 degree day here in Maryland. Blazer started fine in the morning and starting fine in the afternoon. In traffic, and after sitting at a stop light for a few minutes the problem restarted. No SES light. From a stop gave it gas, it accelerated fine until I gave it more gas pedal to accelerate faster. Vehicle hesitated badly so I backed of the gas and it felt normal. I had to keep backing off the pedal to keep it from hhesitating until it final stalled completely. Had to let it sit for over an hour. Check the fuel rail and it had pressure. I couldnt tell exactly as i had no gauge. Turn key back on and pressure built back up. It hesitated and was hard to restart but ran for another 4 miles before doing the same thing again. Let it sit two hours restarted and got it home 5 miles away. Although I still got no. SES light I noticed a discoloration on the ignition coil and replaced it as well as cleaning out the MAF sensor in case it was dirty. But again no codes. This morning started fine and I'm now sitting at the shop. This never repeats itself for any mechanic. Just likes to leave me stranded. Thank you in advance for your help.

i seen what all you done except the cps sensor or it just might be your cat is plugged?

Ok. As requested I'm starting a new thread. I've seen a lot of people who have had this issue throughout several different forums but no one has ever posted a resolution that I have found.I bought the blazer last September. 4.3l spider injectors had 175k miles when purchased and super clean. Last summer on hot days, and only after driving 15 - 20 miles the engine would start to hesitate on acceleration. The more gas pedal I would give it, thee more it would hesitate and lose power until it eventually stalled completely . I could let it sit, cool down for 30 minutes and it would restart. This happened 4 times last summer on hot days and each day it was back in the shop from where I purchased it. Fuel rail pressure is always good. Leak down test was done on the fuel rail and it held. The only code I would get was an intermittment small evap leak. Fuel filter was replaced. After several revisits to the mechanic he replaced the ICM (supposedly), then we entered the fall season, the weather cooled, and I never had the stalling issue. I did however sporadically get the small evap leak code come up when I was always below a half tank of fuel. I'd fill up and and next diagnostics cycle the SES would go off. Fast forward through the winter, no problems other than sporadic SES WHEN UNDER HALF TANK. motor was replaced 2 weeks ago with a new one. 500 miles on the motor and we had our first 80 degree day here in Maryland. Blazer started fine in the morning and starting fine in the afternoon. In traffic, and after sitting at a stop light for a few minutes the problem restarted. No SES light. From a stop gave it gas, it accelerated fine until I gave it more gas pedal to accelerate faster. Vehicle hesitated badly so I backed of the gas and it felt normal. I had to keep backing off the pedal to keep it from hhesitating until it final stalled completely. Had to let it sit for over an hour. Check the fuel rail and it had pressure. I couldnt tell exactly as i had no gauge. Turn key back on and pressure built back up. It hesitated and was hard to restart but ran for another 4 miles before doing the same thing again. Let it sit two hours restarted and got it home 5 miles away. Although I still got no. SES light I noticed a discoloration on the ignition coil and replaced it as well as cleaning out the MAF sensor in case it was dirty. But again no codes. This morning started fine and I'm now sitting at the shop. This never repeats itself for any mechanic. Just likes to leave me stranded. Thank you in advance for your help.

It needs to be tested when it does it.

Run a full fuel pressure test.
Hook up a fuel pressure gauge and drive it untill hot or when itn does it.
Post back fuel pressure reading and readings when it stalls.
If fuel pressure is up to specs when it stalls then check for lose of park to plugs.

Also tap computer for stored or history codes.
If any post back code no.

I was at the shop when I posted the original message and the new mechanic went through everything again and it all checked out. Actually I've replace the cat and muffler 3 weeks ago so a no go on that. I went ahead and replaced the ICM two days ago as it didn't look like it had been replaced as I was told. I had mentioned to the previous mechanic about ensuring there was grease between the ICM and the heat sink. When I pulled the old one off, it looked like silicon grease was on it. Not the white grease supplied with the new one. I took the heat sink and ICM off, cleaned the heat sink extremely well and reinstalled. So far the weather here has not gotten out of the 60's so everything has been running fine. I went on a 100 mile round trip adventure yesterday without incident. It's supposed to be 80 tomorrow so we'll see how it fairs.

The issue with having it tested when it happens is I'm usually alone, or with my 5 year old son when it occurs. Within 30 minutes to an hour the problem dissipates. Not enough time to contact a tow company, wait for them to respond and transport the vehicle to the garage. By that time, the vehicle is operating again. Frustrating.

By CPS, you mean the Cam Position Sensor? How difficult is that to replace?

As I mentioned before, lots of people having this problem but I haven't found anyone following it all the way through to the end. At least I'd like to complete this thread to resolution.

Parts replaced so far:

Motor
Cat
Muffler
Ignition Coil
Ignition control module (cleaned heat sink and replaced grease)
Distributor, Cap, Rotor, wires
took apart and cleaned MAF sensor
Replaced air filter (was very dirty)
Thermostat

Current MPG average is 17.3

Alright, that didn't work guys. Got to my son's daycare, turned off the vehicle and it wouldn't restart. Left it sit 30 minutes and it restarted, drove perfectly fine and got me the 10 miles home. Although, this time it did throw a code directly on startup. I can't get it anywhere now though as it won't restart again. Before I cut the vehicle off and put it in park and gave it some throttle and the throttle response response was terrible and eventually dwindled down to nothing. I don't have anyway currently of pulling off the codes so I'm hoping to let it cool down and run it up to autozone. Guess I will start pricing a code reader out. :banghead:

has anyone tried the old tap test.... bang on the computer??
just a thought,lots of money spent!!

has anyone tried the old tap test.... bang on the computer??
just a thought,lots of money spent!!


I haven't heard of the old tap test

well, not so much a tap test, but start unplugging harnesses and checking for corrosion. spray em out with contact cleaner.

I haven't heard of the old tap test

The old Tap/twist it was used on the older PCM computers to check for circuit board problems.

Not any way to do it on the VCM computers.

As said before it needs tested when it does it.

One test you can do by yourself is hook up a fuel pressure gauge and tape it to outside mirrow or outside windshield and watch fuel pressure while driving and when it does it.

If fuel pressure hold up to specs driving and when it acts up then it is other problems.

But still needs tested when acting up.

Find a good repair shop that will test it for you.

I am having the exact same problem with the exact same symptoms. The failure of the engine sets no codes!!! I have replaced the: fuel pump, fuel filter, rotor, plugs, wires, coil, distributor cap, ICM, plenum gaskets, intake manifold gaskets, fuel regulator, alternator, water pump, coolant temp sensor. I cleaned all connectors and pins. Because of these repairs, the air blend damper door actuator failed (it broke the main gear inside). To repair that consisted of removing the entire dash, replacing the inaccessible part, and reinstalling the dash. Replaced temperature control dash panel. I cleaned all connectors and pins.

In the winter that car runs perfectly.

I am starting to think it's the VCM because the high speed blower setting on the HVAC will not run sometimes too.

Now I think it might be the spider and the MAX injector.

Anyone know how to tell for sure??

HELP!!!

I am having the exact same problem with the exact same symptoms. The failure of the engine sets no codes!!! I have replaced the: fuel pump, fuel filter, rotor, plugs, wires, coil, distributor cap, ICM, plenum gaskets, intake manifold gaskets, fuel regulator, alternator, water pump, coolant temp sensor. I cleaned all connectors and pins. Because of these repairs, the air blend damper door actuator failed (it broke the main gear inside). To repair that consisted of removing the entire dash, replacing the inaccessible part, and reinstalling the dash. Replaced temperature control dash panel. I cleaned all connectors and pins.

In the winter that car runs perfectly.

I am starting to think it's the VCM because the high speed blower setting on the HVAC will not run sometimes too.

Now I think it might be the spider and the MAX injector.

Anyone know how to tell for sure??

HELP!!!

PROPER TESTING WILL TELL FOR SURE.

But best to start your own New Thread/Post.
Saves on hyjacking expense.
And give all information on yours.

You have a lot of replacing but no metion of what has beed tested or what brand of replacement parts or why parts were replaced.

Have you tested fuel pressure?
Have you tested everthing when it is acting up?
Have you put it on a engine capable scanner and read out sensor data and checked for history/past /stored /present codes?
Remember not all problem will set check engine light and hold it on?
Any flashing check engine light when driving?
Does the check engine light come on key bulb check on and go off engine running?
Was your replacement parts AC Delco and Delphi fuel pump?
Auto matc AC controls or regular?
How did your repair break blend door?

What year is your blazer? And let me say, I feel for you and know it's been frustrating. I'd kinda like to work in conjunction with you, compare what we've done versus what we haven't. I actually think having both threads may limit the info we get together, or I'll just have to keep a watchful eye open for your's if and when you open a new thread.

I took the vehicle to my local GM dealer yesterday and basically got a shrug of the shoulder. Hooked up a engine scanner and no level out of spec were discovered. I had discussed with the service mechanic the possibility of the spider injector and nut kit replacement and the basic answer I got was it was worth a shot. I went in to talk to the parts people and they just confused me. 2 different parts guys told me my vehicle doesn't show it has the spider injector. WHAT!?!?! I'm now confused. they price me out 6 injectors and a body kit (?) for $991.00. Woe. Not what I expected. The body kit was $140 so I'm wondering if that may be the actually spider assembly. They didn't have one in the shop so I couldn't look at it. So, do I have the spider connector or not? Sure thought I did based on the research I had done. I don't want to open up the intake and find out I have the wrong part and no one has it in stock.

The nut kit was $40. Weather seems like it will be getting no higher than 70 for a while so this will not repeat itself until it gets hotter. I am going to purchase a fuel pressure gauge as suggested and leave it on and taped up so I can watch the pressure during all range of RPM. Pressure tests have been done by a previous mechanic with passable levels at idle. I leak down test was also done according to the previous mechanic and fuel pressure maintained.

I also want to put out there a few things I had not previously mentioned because I didn't want to be chasing a ghost and this was not the major symptom and as every mechanic I have talked to does not seem to think this is a symptom, but I always have. RPMs when I first start the truck cold are about 800. After the engine has warmed up and stopped at a light with the trans in gear, the RPMs are somewhere inbetween 550 and 600. This is not a rough idle by any means, low, but not rough. I do however get a slight loping of the RPM while stopped and in gear. The RPM will lope from 550 to 650 or any where within that range every 5 seconds or so. It isn't consistent and does it whenever. When driving at 60mph, my RPMs maintain a consistent 2000. I may feel a slight hiccup, and I mean ever so slight. If I wasn't paying so close attention to everything because this thing left me on the side of the road so many times, I would miss it. Also, at this RPM range - 1800 to 2000 throttle response os very poor, seems I can move the gas pedal half the distance without any response from the engine and then it drops down a gear flies up to 2500 RPM. And one last thing, after the truck is warm, and I have gotten somewhere, turned the motor off, put it in park the idle jumps to 750 RPMs then gently falls back down to 550 -600 RPMs. When I come back and restart it, same thing, 750 down to 550. But when I put it in gear, I have virtually no change in RPM idle is not rough, just low.

Just trying to throw everything out there.

MaxisP, don't forget about me if you end up finding a solution, please.

OK! I was trying to be brief. My failure mode is exactly the same as the OP. I have 177,000 mile on the engine.
1996 Chevy S10 Blazer 4x4 4.3 Vortec Vin Code W.
The air blend door actuator breaks because the door cycles each time power is removed and applied. Think of the carriage assy on a printer when you power up. Mine broke the main gear inside and was stuck with the heater full on.
Brand new fuel pump.
Cannot test anything when engine will not start.
It sets no codes. Every now and then I get evap codes, because of the gas cap.
No check engine lights for this problem.
Replacement parts are from Autozone usually.
Why would I open a new thread for the exact same problem?

The car runs fine when the ambient is less than 80 degrees. I went from Las Vegas to Phoenix and back last week when it was in the 60s.

I ran across a mechanic who said their kid had the same car, and it had the same problem. He said that they spent an entire day chasing wires under the dash to fix this problem. When I pulled the dash, I cleaned all the contacts I could find. I thought that would fix any wiring problems under the dash. I found two relays I did not take the time to identify. One was stuck on the HVAC covers and was wide and rectangular. Another was wrapped in foam and installed into the fascia. I think one is the HVAC high fan speed.

Also, I don't know if this is a hint, but my HVAC fan will stop running at the high speed setting when it gets warm too. This is a new fan, and fan speed regulator and control plate.
Another hint is opening the hood seems to cool off whatever is stopping the engine, so I think it's under the hood , not the dash wiring. That's why I thought it was the ICM to begin with. I replaced that last summer and drove from Las Vegas to Tucson and back in the heat of the summer. So I thought I had fixed it.
That's why I am thinking maybe the VCM or spider and injector.
I also know that I need to change my 4X4 vacuum switch, but that's unrelated.
An expert would help here.

Sorry in advance.
Also, the HVAC high speed fan did not use to come on at all. I replaced the fan and the fan control inductor and the switch. Did not make a difference. Then I changed the engine coolant temperature sensor, located near the thermostat and the high fan worked again. Until it gets hot outside.

That is leading me to the VCM. There appears to be a logic command to the high speed fan relay that allows the fan to run when it's colder outside. Then shuts off if it is outside the allowed temp range. Maybe the VCM is doing the same for the ignition or injector, to prevent a perceived overheat problem that doesn't exist.

I don't know.

To repeat, my symptoms are the same as the OP. Only when it's warm outside. It feels like vapor lock, or running out of gas. Car runs until the problem starts. If you press accel too much it dies off, but runs at idle until it stops eventually. Open the hood to cool off and the car starts right up, no codes, no saved codes, no problem until it does it again. Turning the key runs the fuel pump until the relay shuts it off seconds later. But the car does not start.

This is a very common problem on the internet. But no solutions.

Experts?

OK! I was trying to be brief. My failure mode is exactly the same as the OP. I have 177,000 mile on the engine.
1996 Chevy S10 Blazer 4x4 4.3 Vortec Vin Code W.
The air blend door actuator breaks because the door cycles each time power is removed and applied. Think of the carriage assy on a printer when you power up. Mine broke the main gear inside and was stuck with the heater full on.
Brand new fuel pump.
Cannot test anything when engine will not start.
It sets no codes. Every now and then I get evap codes, because of the gas cap.
No check engine lights for this problem.
Replacement parts are from Autozone usually.
Why would I open a new thread for the exact same problem?

The car runs fine when the ambient is less than 80 degrees. I went from Las Vegas to Phoenix and back last week when it was in the 60s.

I ran across a mechanic who said their kid had the same car, and it had the same problem. He said that they spent an entire day chasing wires under the dash to fix this problem. When I pulled the dash, I cleaned all the contacts I could find. I thought that would fix any wiring problems under the dash. I found two relays I did not take the time to identify. One was stuck on the HVAC covers and was wide and rectangular. Another was wrapped in foam and installed into the fascia. I think one is the HVAC high fan speed.

Also, I don't know if this is a hint, but my HVAC fan will stop running at the high speed setting when it gets warm too. This is a new fan, and fan speed regulator and control plate.
Another hint is opening the hood seems to cool off whatever is stopping the engine, so I think it's under the hood , not the dash wiring. That's why I thought it was the ICM to begin with. I replaced that last summer and drove from Las Vegas to Tucson and back in the heat of the summer. So I thought I had fixed it.
That's why I am thinking maybe the VCM or spider and injector.
I also know that I need to change my 4X4 vacuum switch, but that's unrelated.
An expert would help here.

Why would you open a new thread for the exact same problem?


For one reason it saves on hyjacking cost.

When you hyjack another person's post having two different vechicals and usualy two different problems it gets very confusing.
I very seldom find two differnt vechicals problems with the same answer.
First thing on yours.
If you have a no start you can check fuel pressure for up to specs and loose of spark to all plugs to start with.

If you want expert help try all a data DIY online sub.
And go threw the proper testing.

This is the same problem.

What makes you think that there has not been the proper testing?

The OP thought it was the same also.

Comparing notes helps us.

Splitting this thread does not help.

I answered but someone moved my answers to a different thread.

This is two years running for me and goes away in the winter.

Bought car 133, 000 then:

Fuel pump failed, replaced.
AC failed, rebuilt. Battery fails, replace. Replace HVAC fan, iductor control and dash panel. No high fan setting available in summer.
ICM failed, replaced. While there changed coil, cap, rotor, wires, s plugs, PVC. Drove 1000 miles in the southwest summer, no problems. Test EGR OK.
Torque converter lockup solenoid failed, replaced.
Car fails when temp gets up to 80 degrees.
Automatic tensioner, alternator bearings failed, water pump bearings, idle pulley. Replace.
Change engine coolant temperature sensor.
Hit object (rock?), radiator fan explodes. Replace all belts hoses, radiator fan, thermostat and radiator.
Intake manifold gasket blew. Peanut butter in engine. Cleaned and replaced gaskets, seals and o-rings. Replaced fuel regulator. Discover vapor scavenge not connect to back of car. Connect. Replace all vacuum lines. Original light whistle on acceleration disappears.
Check engine light. Bad fuel cap.
Air temperature damper door actuator fails. High heat on full time. Remove dash and replace.
Car runs 2000 miles after intake manifold gasket repair no codes, no problems 20 miles a gallon, up from 17.
Ambient temp 80 and car fails after 25 miles on the freeway. Just get off the freeway safely and coast into parking lot. Cool off 10 minutes, then go 6 miles home with no problem.

Hey! They change the gas here in the spring for the summer, by adding or taking away alcohol and back in the winter. Do they do that in other states?

This is the same problem.

What makes you think that there has not been the proper testing?

The OP thought it was the same also.

Comparing notes helps us.

Splitting this thread does not help.
Looks like it has done been split to a new thread.
Not by me.
But thanks to someone.
Good deal.
Now
If you want help give us less head and some answers to post 2.

Fuel pressure 58 changes with accel or idle speed.

This problem is two years running for me and goes away in the winter.

What I have done. Bought car 133, 000 then:

Fuel pump failed, replaced.
AC failed, rebuilt. Battery fails, replace. Replace HVAC fan, iductor control and dash panel. No high fan setting available in summer.
ICM failed, replaced. While there changed coil, cap, rotor, wires, s plugs, PVC. Drove 1000 miles in the southwest summer, no problems. Test EGR OK.
Torque converter lockup solenoid failed, replaced.
One month later, car fails when temp gets past 80 degrees.
Automatic tensioner, alternator bearings failed, water pump bearings, idle pulley. Replace.

Change engine coolant temperature sensor.
Hit object (rock?), radiator fan explodes. Replace all belts hoses, radiator fan, thermostat and radiator.
Intake manifold gasket blew. Peanut butter in engine. Cleaned and replaced gaskets, seals and o-rings. Replaced fuel regulator. Discover vapor scavenge not connect to back of car. Connect. Replace all vacuum lines. Original light whistle on acceleration disappears.
Check engine light. Bad fuel cap.
Air temperature damper door actuator fails, because they fail when they are this old and you take the battery on and off. High heat on full time. Remove dash and replace.

Car runs 2000 miles after intake manifold gasket repair no codes, no problems 20 miles a gallon, up from 17.

Ambient temp 80 and car fails after 25 miles on the freeway. Just get off the freeway safely and coast into parking lot. Cool off 10 minutes, then go 6 miles home with no problem.

I cannot test something acting up because nothing is acting up until it gets hot. No codes. no codes in memory.

Hey! They change the gas here in the spring for the summer, by adding or taking away alcohol and back in the winter. Do they do that in other states?

This is two years running for me and goes away in the winter.

Bought car 133, 000 then:

Fuel pump failed, replaced.
AC failed, rebuilt. Battery fails, replace. Replace HVAC fan, iductor control and dash panel. No high fan setting available in summer.
ICM failed, replaced. While there changed coil, cap, rotor, wires, s plugs, PVC. Drove 1000 miles in the southwest summer, no problems. Test EGR OK.
Torque converter lockup solenoid failed, replaced.
Car fails when temp gets up to 80 degrees.
Automatic tensioner, alternator bearings failed, water pump bearings, idle pulley. Replace.
Change engine coolant temperature sensor.
Hit object (rock?), radiator fan explodes. Replace all belts hoses, radiator fan, thermostat and radiator.
Intake manifold gasket blew. Peanut butter in engine. Cleaned and replaced gaskets, seals and o-rings. Replaced fuel regulator. Discover vapor scavenge not connect to back of car. Connect. Replace all vacuum lines. Original light whistle on acceleration disappears.
Check engine light. Bad fuel cap.
Air temperature damper door actuator fails. High heat on full time. Remove dash and replace.
Car runs 2000 miles after intake manifold gasket repair no codes, no problems 20 miles a gallon, up from 17.
Ambient temp 80 and car fails after 25 miles on the freeway. Just get off the freeway safely and coast into parking lot. Cool off 10 minutes, then go 6 miles home with no problem.

Hey! They change the gas here in the spring for the summer, by adding or taking away alcohol and back in the winter. Do they do that in other states?

yes, they adjust the gas here well, I don't think it has much to do with this though. One thing I did want to ask you though is you said you get the evap small leak code. Have you replaced the gas cap and has that code still come up? Mine just shot that code off again today and as usual I was low on fuel. I'm thinking there may be something to this. when you replaced your vacuum lines, did you replace the one that went to fuel pump? I believe there is one there.

Anyway, I purchased a fuel pressure test gauge today and hooked it up to see what's going on with the fuel pressure. So far, key turned on it jumps up above 60psi then immediately goes to 55psi. Start the motor and it jumps up over 60 and immediately down to 55 again. At idle the needle jiggles at 55psi. I brought the RPMs up to 3000 and as soon as I press on the gas pedal it jump up to at least 65psi then immediately down to 55psi while holding at 3000rpms. I let off the gas and the pressure drops below 50psi then immediately back up to 55. Now, when I turn the key off, then pressure drops down to 43-44psi. If I turn the ignition on, but not start the vehicle it comes back up above 60 then drops back down to 55. Go through the same cycle, turn off the ignition and pressure drops to 43-44psi. I'm currently doing a leak down test on it so we'll see what happens next. I've hooked it up temporarily so I can watch it while driving.

Fuel pressure 58 changes with accel or idle speed.

This problem is two years running for me and goes away in the winter.

What I have done. Bought car 133, 000 then:

Fuel pump failed, replaced.
AC failed, rebuilt. Battery fails, replace. Replace HVAC fan, iductor control and dash panel. No high fan setting available in summer.
ICM failed, replaced. While there changed coil, cap, rotor, wires, s plugs, PVC. Drove 1000 miles in the southwest summer, no problems. Test EGR OK.
Torque converter lockup solenoid failed, replaced.
One month later, car fails when temp gets past 80 degrees.
Automatic tensioner, alternator bearings failed, water pump bearings, idle pulley. Replace.

Change engine coolant temperature sensor.
Hit object (rock?), radiator fan explodes. Replace all belts hoses, radiator fan, thermostat and radiator.
Intake manifold gasket blew. Peanut butter in engine. Cleaned and replaced gaskets, seals and o-rings. Replaced fuel regulator. Discover vapor scavenge not connect to back of car. Connect. Replace all vacuum lines. Original light whistle on acceleration disappears.
Check engine light. Bad fuel cap.
Air temperature damper door actuator fails, because they fail when they are this old and you take the battery on and off. High heat on full time. Remove dash and replace.

Car runs 2000 miles after intake manifold gasket repair no codes, no problems 20 miles a gallon, up from 17.

Ambient temp 80 and car fails after 25 miles on the freeway. Just get off the freeway safely and coast into parking lot. Cool off 10 minutes, then go 6 miles home with no problem.

I cannot test something acting up because nothing is acting up until it gets hot. No codes. no codes in memory.

Hey! They change the gas here in the spring for the summer, by adding or taking away alcohol and back in the winter. Do they do that in other states?

Yes they go from a winter to a summer blend.
Your fuel pressure is low.
4.3 V6 specs are 60/66 lbs.
You should see 64-65 cold start and 62-64 running on road.

If you did not replace the fuel pump with a Delphi pump you may be in bad shap there.
Airtex and other aftermarket fuel pumps are junk.
Very high fail rate and almost all are low on pressure.

Needs to be tested when it quits or acts up.

I would hook up a fuel pressure gauge and tape it to outside windshield or out side mirrow and watch fuel pressure on the road and see if it drops below specs when it quits or acts up.

If not you need to check for loss of spark to plugs when it quits.

Also with a light whistle you need to check back pressure on exhaust.

If it is acting up that bad it should have some stored or past or present code or data reading out of range..
Is fuel trim data holding good or going high or low.
What is the camshaft retart setting reading?

I have put on three gas caps since I got the car. The caps have a space above the seal that allows the seal to be pushed up higher and higher when you tighten it. Lately I just push the seal back down until I get gas again. It goes away.

My scavenge solenoid was connected to a line that went down under the firewall bulge, but I found it wasn't connected. That solenoid opens to pull the vapor for a few seconds after you turn off the key.

My fuel pressure behavior is very similar. It starts at 58 and varies like you stated.

I was wondering if the alcohol dis-associates from the gas at high temp and causes a vapor lock type situation.

At one time, I thought it was a fuel pump motor overheating and shutting off problem, so I kept the tank full to make sure there was enough heatsink (the reason it's in the tank) to cool the motor, but that didn't work last year.

I do have a problem with the vacuum switch on the transfer case needs to be replaced. That's the shift assist for 4WD low.

I would like to know if someone with a similar problem of the car stalling at hot ambient temperatures tracked it back to the fuel injector, spider or VCM.

There are thousands of this type of problem for the engine in every application with the same problem when Googled. None show solved.

OK,
I am waiting for it to warm up again.

Fuel pressure at 58 idle, ~65 @ 3000 rpm. Will check driving around.

Whistle I had since bought the car was leaking intake manifold seal in back. Fixed.

What's a good way to check spark when you have to start the car too?

Once, I got ICM voltage high code. That indicated floating grounds to me so I went through all cables and ground connections and cleaned them and polished them and that went away. They were untouched since the factory installed them.

No other codes stored. I drove around with an engine status monitor for awhile and got no out of spec readings on any sensor. Fuel trim was unremarkable.

I don't know about any change in the camshaft that would run cold and stop the engine hot. I would be interested to know how that would work.

OK,
I am waiting for it to warm up again.

Fuel pressure at 58 idle, ~65 @ 3000 rpm. Will check driving around.

Whistle I had since bought the car was leaking intake manifold seal in back. Fixed.

What's a good way to check spark when you have to start the car too?

Once, I got ICM voltage high code. That indicated floating grounds to me so I went through all cables and ground connections and cleaned them and polished them and that went away. They were untouched since the factory installed them.

No other codes stored. I drove around with an engine status monitor for awhile and got no out of spec readings on any sensor. Fuel trim was unremarkable.

I don't know about any change in the camshaft that would run cold and stop the engine hot. I would be interested to know how that would work.
You need to get the fuel pressure up to par and make sure it is not dropping off when it acts up.
After you get that fixed then check for lose of spark if still acting up.

To check spark I hook up a push button starter button to starter system.
Make sure it is in park before pushing button and pull coil wire or wire off of spark plug and key on and crank engine over.
You can use a screw drive in end of wire or a spark jumper tester to see if you have good hot blue loud spark.

Spark should jump 1 1/4 in or more and snap a good blue spark.

Camshaft retard setting is the position of rotor to plug wires terminals.
Should read out as close to - or plus 0 degrees as you can get it.
Not over 1 or 2 degrees - or plus.

If reading 25 degrees you have sensor problem.

If over 3 degrees off it increase the spark to much and overloads coil and ign system.

yes, they adjust the gas here well, I don't think it has much to do with this though. One thing I did want to ask you though is you said you get the evap small leak code. Have you replaced the gas cap and has that code still come up? Mine just shot that code off again today and as usual I was low on fuel. I'm thinking there may be something to this. when you replaced your vacuum lines, did you replace the one that went to fuel pump? I believe there is one there.

Anyway, I purchased a fuel pressure test gauge today and hooked it up to see what's going on with the fuel pressure. So far, key turned on it jumps up above 60psi then immediately goes to 55psi. Start the motor and it jumps up over 60 and immediately down to 55 again. At idle the needle jiggles at 55psi. I brought the RPMs up to 3000 and as soon as I press on the gas pedal it jump up to at least 65psi then immediately down to 55psi while holding at 3000rpms. I let off the gas and the pressure drops below 50psi then immediately back up to 55. Now, when I turn the key off, then pressure drops down to 43-44psi. If I turn the ignition on, but not start the vehicle it comes back up above 60 then drops back down to 55. Go through the same cycle, turn off the ignition and pressure drops to 43-44psi. I'm currently doing a leak down test on it so we'll see what happens next. I've hooked it up temporarily so I can watch it while driving.

Alright, no pressure reading on the gauge this morning. turned the key over started right away. Cold start 58psi with ambient air temp at 45 degrees. While driving within the first 15 minutes, under acceleration, the pressure would increase from 58 to 67psi. 67psi under acceleration, 58 at cruising, and 58 at idle. By the time I reached worked, 20 or so miles away, acceleration pressure was about 64, cruising was 55 and idle was 55psi.

Occasionally under accelleration, I would get a split second massive spike that I couldn't even tell you how high it got because it happens way to fast. All I can say is massive spike for a fraction of a second.

Reach work, turn the motor off and pressure dropped to 42psi. turned the key on, pressure went up to 62psi.

The fuel pressure gauge wasn't the esiest of things to line up and get on for some reason and is only finger tight based on instructions. I did not feel any leaks from the connection so I hope the leak down is accurate. This evening I plan on removing the gauge and reseating it and redoing the leak down test to be sure.

Alright, no pressure reading on the gauge this morning. turned the key over started right away. Cold start 58psi with ambient air temp at 45 degrees. While driving within the first 15 minutes, under acceleration, the pressure would increase from 58 to 67psi. 67psi under acceleration, 58 at cruising, and 58 at idle. By the time I reached worked, 20 or so miles away, acceleration pressure was about 64, cruising was 55 and idle was 55psi.

Occasionally under accelleration, I would get a split second massive spike that I couldn't even tell you how high it got because it happens way to fast. All I can say is massive spike for a fraction of a second.

Reach work, turn the motor off and pressure dropped to 42psi. turned the key on, pressure went up to 62psi.

The fuel pressure gauge wasn't the esiest of things to line up and get on for some reason and is only finger tight based on instructions. I did not feel any leaks from the connection so I hope the leak down is accurate. This evening I plan on removing the gauge and reseating it and redoing the leak down test to be sure.

Fuel pressure is a little low.
You should be seeing 62 t0 64 normal speed crusing.

Make sure direct full pressure or with return luine blocked/pluged is 95-105 lbs.

If good full pressure the fuel pressure regulator may be off.

But you need to drive it long enought for it to act up or quit and check fuel pressure then.

If it holds good then go for a spark / test when no start.

Let us know how it goes.

alright, looks like I definately have a leak down prob. Assuming this is most likely caused by the spider assembly/cpi nut kit/fuel regulator leaking. Correct? Is it possible this could be caused by the fuel pump?

Last question, could this also be causing the stall issue on hot days. Leak possible getting worse on hotter days and flooding the intake? I couldn't imagine all the cylinders getting too much fuel. Any thoughts? I guess I could also take out the spark plugs to see if I had fouled out any. it's only been about 3 weeks since the motor was replaced and spark plugs were replaced at that time. I just don't readily see how the issue could be related.

alright, looks like I definately have a leak down prob. Assuming this is most likely caused by the spider assembly/cpi nut kit/fuel regulator leaking. Correct? Is it possible this could be caused by the fuel pump?

Last question, could this also be causing the stall issue on hot days. Leak possible getting worse on hotter days and flooding the intake? I couldn't imagine all the cylinders getting too much fuel. Any thoughts? I guess I could also take out the spark plugs to see if I had fouled out any. it's only been about 3 weeks since the motor was replaced and spark plugs were replaced at that time. I just don't readily see how the issue could be related.

leak down can be fuel pump check valve or hose or line or nut kit or fuel pressure regulator.

Stall can be cause by low or no fuel pump pressure.
Leak inside intake or leaking pressure regulator can cause a hard or flooded restart.

First thing confirm good strong fuel pump pressure at all times.
And then go from there.
Get a fuel pump pressure gauge on it and drive it 30 or more minutes watching pressure untill it quits or acts up.
A good pump will deliver 95-105 lbs of direct fuel pressur.

That sounds right. When it gets too hot outside, maybe the pintles or injector leak and the car floods hot.
But I would think that there is a code for too rich, beyond tolerances.
When my fuel pump went out the code set was for one bank too lean, it was symptom of low fuel pressure.

That sounds right. When it gets too hot outside, maybe the pintles or injector leak and the car floods hot.
But I would think that there is a code for too rich, beyond tolerances.
When my fuel pump went out the code set was for one bank too lean, it was symptom of low fuel pressure.

Fuel pressure problems do not always set code.
If pump quits all at once the computer can not tell anything
That is why they make fuel pressure gauges.
Get the pressure gauge on it and drive it and wtch it.
Post back all pressure readings.

http://www.flickr.com/photos/24145378@N05/5629352375/Timing advance.
It's -20 at start and goes to -40 on acceleration.

Short trim timing -2 to -5 on bank 1 and 2 and about the same for both banks long term.

There are no codes stored, none pending and none permanent.

Tomorrow is going to be hot I will see if I can duplicate failure.

I currently have a pressure gauge hooked up to the schrader valve on the fuel rail. Can you explain how where to place a pressure gauge to test the pump itself prior to being adjusted by the regulator?

I wanted to run through an entire tank of gas and get pressure reading throughout. If memory serves correct, my problems usually are when I am below a half tank of gas and when it is above 80 degrees outside. Interestly enough, Once I hit half a tank, pressure readings became a little more eradic. Specs while driving were about the same as previously reported, however, the needle was much more "jumpy" or "jiggly" or eradic. I should take a video and upload it. Now for the more interesting part. When parked and in nuetral, and below a half a tank, I would rev the engine I would get a smaller spike in pressure as before but as I revved up to 3000, the higher the rev, the lower the pressure would go (ended up below 55. Again, previously I would get a spike in pressure and an immeadiate return to 55-58 psi. This occurred when I was below half a tank. I also do have a leakdown issue that has seemed to increase now that I am below half a tank. I am going to check it at hour intervals today and record the pressure. I waited to fill up so I could get these readings and will subsequently record the same reading after fill up. To bad I waited to fill up though, gas around here went up another 6 cents per gallon since yesterday.

I've taken some videos to at least show what I'm talking about, the first video is to give some perspective on the pressure gauge dial as it's a little hard to video it close up while driving. Here is the link to the first video. you should be able to see the rest in my channel. Let me know if you cannot.

http://www.youtube.com/user/mcdon26?feature=mhsn#p/u/5/RbMa2ett1FY

I've taken some videos to at least show what I'm talking about, the first video is to give some perspective on the pressure gauge dial as it's a little hard to video it close up while driving. Here is the link to the first video. you should be able to see the rest in my channel. Let me know if you cannot.

http://www.youtube.com/user/mcdon26?feature=mhsn#p/u/5/RbMa2ett1FY

Good pictures.

Looks like you have fuel pressure regulator and fuel pump problems both.

Bounching or Flopping gage indicates bad pump or wiring or voltage to it.

Block/plug return line or tap on direct to fuel filter in line and see what the pressure goes to.

Good strong pump should deliver 95-105 lbs. direct pressure.
Running on road regulated fuel pressure should run 62-64 lbs.

Drive it until it acts up or quites and then check pressure.
Post back fuel pressure when acting up or quits.

The only true test on a fuel pump is to check the direct fuel pressure from fuel pump.
A quick test is to block off the return line and see if fuel pressure comes up to 95-105 lbs.
But do not run the pump at full pressure very long.
Also when testing fuel pump and pressure you need to tape a gauge to outside windshield or outside mirror and drive it on the road for 20 -30 minutes
until the pump gets has run a while to check for a pump fading out after hot.

Hard to start cold or hot and fuel pressure testing guide lines.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.
If pump has full pressure with return line blocked and low pressure without it blocked most usually the fuel pressure regulator is leaking or not holding pressure.
Later V6 and V8 gm engines should have 60-66 fuel pressure.
Cold start should be 64-65 lbs of pressure.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
Do not leave home without it.
Engine running should be 60-66 lbs pressure depending on engine load.
Full pressure with return pinched off should be 95-105 or more.
And if it has a fast leak down after shut off you have a leak in system.
Drive untill it quits or acts up.
And check fuel pressure then.
Post back fuel pressure readings.

Good pictures.

Looks like you have fuel pressure regulator and fuel pump problems both.

Bounching or Flopping gage indicates bad pump or wiring or voltage to it.

Block/plug return line or tap on direct to fuel filter in line and see what the pressure goes to.

Good strong pump should deliver 95-105 lbs. direct pressure.
Running on road regulated fuel pressure should run 62-64 lbs.

Drive it until it acts up or quites and then check pressure.
Post back fuel pressure when acting up or quits.

Thank for the replies.

My leak down is not super fast, we're talking about 9 psi an hour I lose from shut off. Strangely enough, the hotter it got outside, the slower the pressure loss was. At one point I actually gained 2 psi. Here's what that break down looks like.

Turn off motor 42 PSI
1 hour check drop 9PSI to 33PSI
2nd hour check drop 9 psi 22PSI
3 hour check drop 3 psi to 19PSI
3.5 hour check up 1 psi to 20PSI
4 hour check up 1 psi to 21 PSI

At least you're confirming my thought I may have two issues, the question for me is which to fix first. I'm leaning towards the regulator, spider assembly (if I have one, I still haven't gotten confirmation yet.) and cpi nut kit. my thought is, if I'm getting adequate pressure to the fuel rail to stay running before I have this stall problem when hot, and my regulator/nut kit is leaking causing a flooding issue, a new fuel pump with higher pressure will make this problem worse. Or, I can just wait for this to happen again and see what that tells me.

I will have to locate the return line and attempt to pinch it off as suggested. Vice grips/pliers work? any recommendations on this?

Doesn't look like I will have any problems today because we never got to 80 and we have a storm coming in which has drop the temp considerably. Wednesday seems to be the high temp day so we'll see what happens then.

At least I feel like I'm getting somewhat closer to a resolution, just would hate to replace the fuel pump, and injector assemblies and still have the issue.

Thank for the replies.

My leak down is not super fast, we're talking about 9 psi an hour I lose from shut off. Strangely enough, the hotter it got outside, the slower the pressure loss was. At one point I actually gained 2 psi. Here's what that break down looks like.

Turn off motor 42 PSI
1 hour check drop 9PSI to 33PSI
2nd hour check drop 9 psi 22PSI
3 hour check drop 3 psi to 19PSI
3.5 hour check up 1 psi to 20PSI
4 hour check up 1 psi to 21 PSI

At least you're confirming my thought I may have two issues, the question for me is which to fix first. I'm leaning towards the regulator, spider assembly (if I have one, I still haven't gotten confirmation yet.) and cpi nut kit. my thought is, if I'm getting adequate pressure to the fuel rail to stay running before I have this stall problem when hot, and my regulator/nut kit is leaking causing a flooding issue, a new fuel pump with higher pressure will make this problem worse. Or, I can just wait for this to happen again and see what that tells me.

I will have to locate the return line and attempt to pinch it off as suggested. Vice grips/pliers work? any recommendations on this?

Doesn't look like I will have any problems today because we never got to 80 and we have a storm coming in which has drop the temp considerably. Wednesday seems to be the high temp day so we'll see what happens then.

At least I feel like I'm getting somewhat closer to a resolution, just would hate to replace the fuel pump, and injector assemblies and still have the issue.

Pinch the rubber part of line.
Vise grips is a little hard on hose.
They make a special hose pinch tool or just plug return line.

IF FUEL PUMP DOES NOT MEET ALL PRESSURE SPECS AND TEST BETTER REPLACE IT.
And use A delphi pump.
Airtex and aftermarket pumps are junk.

Does you fuel lines go into top of engine or into rear intake?

fuel lines go into the back of the intake. That is where the schrader valve is.

fuel lines go into the back of the intake. That is where the schrader valve is.

You have the nut kit set up then.
Another place for it to leak off fuel pressure.

You have the nut kit set up then.
Another place for it to leak off fuel pressure.

which also means the spider assembly correct?

It's a shame because the motor was just replaced 3 weeks ago and the mechanics told me I needed to replace the injector O rings. They only charged me parts cost because the intake was apart. Wish I had known I would have had everything replaced.

GM dealer says I don't have the spider assembly but they call it a injector body kit. Runs about 150.00

which also means the spider assembly correct?

It's a shame because the motor was just replaced 3 weeks ago and the mechanics told me I needed to replace the injector O rings. They only charged me parts cost because the intake was apart. Wish I had known I would have had everything replaced.

GM dealer says I don't have the spider assembly but they call it a injector body kit. Runs about 150.00

Strange I do not remember any injector O rings on that set up.
But a lot of pressure regulators leak on them.
Good luck.

I'm thinking they replaced O rings in the nut kit. The one at the dealer I saw had them. Looking for confirmation I do have the spider assembly though. The nut kit looks right just not sure of the spider assembly. Thinking if replacing both the fuel pump and regulator, assembly and nut kit all this weekend.

Mcdon,
It's up to 90 degrees today in Las Vegas. I drove the car around from 2:00 to 4:00 with the scantool on, but not the fuel pressure gauge. The scantool reports fuel usage,
I was trying to get the car to fail. So I drove around through drive thrus, parking lots and side streets. Stopping and idling. Run the engine at 2000 rpm when parked. The coolant went up to 210 for most of the trip. I turned off the engine in parking lots, sat in traffic at lights ran 2-3 miles at a time and the car ran fine. I tried to get it to heat up and fail.
I sat at home in the driveway for 30 minutes at the end with full AC on and the car started 5 times no problem. Drove the circuit again with no problems.
Since I put another heatsink on the back of the existing ICM heatsink, using silver CPU paste in between, and moved it off the hot coil bracket mounted on the intake manifold, the car has not failed.

Mcdon,
It's up to 90 degrees today in Las Vegas. I drove the car around from 2:00 to 4:00 with the scantool on, but not the fuel pressure gauge. The scantool reports fuel usage,
I was trying to get the car to fail. So I drove around through drive thrus, parking lots and side streets. Stopping and idling. Run the engine at 2000 rpm when parked. The coolant went up to 210 for most of the trip. I turned off the engine in parking lots, sat in traffic at lights ran 2-3 miles at a time and the car ran fine. I tried to get it to heat up and fail.
I sat at home in the driveway for 30 minutes at the end with full AC on and the car started 5 times no problem. Drove the circuit again with no problems.
Since I put another heatsink on the back of the existing ICM heatsink, using silver CPU paste in between, and moved it off the hot coil bracket mounted on the intake manifold, the car has not failed.

Did you use a heatsink exactly like the original? and do you have pictures of your setup? how/where did you mount it? I know there are plenty of available places to connect up to, just curious of your setup. Glad to here it didn't fail for you today.

ok guys, any objections to this? http://cgi.ebay.com/ebaymotors/Delphi-FJ10565-Spider-Injector-V6-MFI-Multiport-_W0QQcmdZViewItemQQfitsZYearQ3a1996Q7cModelQ3aBlaz erQ7cMakeQ3aChevroletQQhashZitem43a665351cQQitemZ2 90554459420QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAcc essories#ht_4400wt_939

It's cheaper on Amazon.

http://www.amazon.com/Delphi-FJ10565-Fuel-Injector/dp/B001J63ILW/ref=au_pf_pfg_s?ie=UTF8&Model=Blazer|420&n=15684181&s=automotive&Make=Chevrolet|47&Year=1996|1996&newCar=1&carId=001

I am almost to that point too. Just a couple of more tests.

ok guys, any objections to this? http://cgi.ebay.com/ebaymotors/Delphi-FJ10565-Spider-Injector-V6-MFI-Multiport-_W0QQcmdZViewItemQQfitsZYearQ3a1996Q7cModelQ3aBlaz erQ7cMakeQ3aChevroletQQhashZitem43a665351cQQitemZ2 90554459420QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAcc essories#ht_4400wt_939

If it is Delphi it has got to be good.
But that does not fix the fuel pump.
MAKE SURE WIRING AND GROUNDS AND POWER FEED TO IT ARE GOOD AND GO WITH A DELPHI oem PUMP SETUP TO.

alright, hold the press, I was about to pull the trigger on the set from Amazon when I went out for another look at the motor. MT, my fuel lines go into the top of the intake, not the back as I previously thought. I hate to get into this thing and have the wrong parts. I don't want to be out 200.00 bucks.

Maxis - any word on what heat sink you used and where you mounted it. You have any pictures?

alright, hold the press, I was about to pull the trigger on the set from Amazon when I went out for another look at the motor. MT, my fuel lines go into the top of the intake, not the back as I previously thought. I hate to get into this thing and have the wrong parts. I don't want to be out 200.00 bucks.

Maxis - any word on what heat sink you used and where you mounted it. You have any pictures?

No nut kit in there than.
The picture on Amazon is the right one for the line in top setup.
But I would just check/replace the fuel pressure regulator.
And check out /replace fuel pump.
A good delphi pump unit will hurt way over 200$

No nut kit in there than.
The picture on Amazon is the right one for the line in top setup.
But I would just check/replace the fuel pressure regulator.
And check out /replace fuel pump.
A good delphi pump unit will hurt way over 200$

thanks, yes I plan on replacing both the fuel pump and the spider assembly at the same time, or I should say same weekend. Good thing about the new spider assembly that was listed on amazon is that it includes the fuel pressure regulator

Ok here I am. Sorry for the wrong part, I thought your intake was different. I don't have a nut kit either. Lines go into the top of the injector.

Today's test. Drive 45 minutes, stop 3 times. Go on freeway 30 miles. Start fuel pressure test.
58 start up, on demand, pressure rises to to 65. Falls to 58 at idle.

Turn off engine.
Pressure drops to 55 in seconds. No further drop in pressure. One hour later pressure at 50 engine cold.

I don't think there is a spider problem, or them leaking hot.

McD, did you press the pressure relief before your tests? Because you may have been leaking down an air slug at the top of the valve.

Drive 3 miles around the Las Vegas Speedway area. Gas pressure never varies from previous settings. A little needle bounce from speed bumps.
The scan tool shows no problems.

Removed pressure tester drove 65 miles around beltway.
Car ran fine.

I wrote a detailed explanation of the heat sink and the site returned an error when I saved it.

ICM heat sink

I got an old scrap heat sink from something. I trimmed it to the same size as the original. Using the original holes as a template I drilled matching holes in the scrap heat sink. Using new long bolts and nuts I assembled ICM/silver paste/stock heat sink facing out/silver paste/scrap heat sink facing out the other way/U bracket.

Using a piece of aluminum sheet, I made a "serif" U bracket that matched the coil mount bracket and mounted the assembly on the old bracket. The silver paste is used to thermally connect a CPU or chip to a heat sink.

Reconnect.

Car has not failed since.

ICM heat sink

I got an old scrap heat sink from something. I trimmed it to the same size as the original. Using the original holes as a template I drilled matching holes in the scrap heat sink. Using new long bolts and nuts I assembled ICM/silver paste/stock heat sink facing out/silver paste/scrap heat sink facing out the other way/U bracket.

Using a piece of aluminum sheet, I made a "serif" U bracket that matched the coil mount bracket and mounted the assembly on the old bracket. The silver paste is used to thermally connect a CPU or chip to a heat sink.

Reconnect.

Car has not failed since.

Got a failure today. I have a video I am uploading so everyone can see what my experience is. According to the truck outdoor temp sensor it got to 94 today. I had no issues driving home at all. Once I got home, I turned the key off and pressure dropped to 42ish as it always has. When I turned the key back on, I got no movement in pressure what so ever. repeated several times with no movement. and the truck would not start. I decided to hit the pressure relief valve on the pressure gauge to see if I was potentially clogged or vapor locked. I relieved all the pressure and turned the key on. I could here the fuel pump had kicked on, I was hearing it from under the left side of the dashboard. Pressure increased some, but as the fuel pump ran to build pressure as it should, but it only jiggled in placed with no great increase in pressure. Once the videos upload, I will post links so you can see what i'm talking about. Peace

video 1 failed fuel pump (http://www.youtube.com/user/mcdon26?feature=mhum#p/a/u/1/py1-0GukYM8)

video 2 no fuel pressure (http://www.youtube.com/user/mcdon26?feature=mhum#p/a/u/0/ZZx87yw-nTQ)

sorry for the scratchy videos.

All signs pointing to Fuel pump alone???

went out to the truck an hour after it sat and turned the key on, fuel pressure went back to normal and truck start on third crank

video 1 failed fuel pump (http://www.youtube.com/user/mcdon26?feature=mhum#p/a/u/1/py1-0GukYM8)

video 2 no fuel pressure (http://www.youtube.com/user/mcdon26?feature=mhum#p/a/u/0/ZZx87yw-nTQ)

sorry for the scratchy videos.

All signs pointing to Fuel pump alone???

yes and no.
May be not all but most or no 1 problem .

No fuel pressure points to fuel pump fail but you need to confirm good power and ground to it when it has no pressure.

About 5 lbs Low regulater fuel pressure may be bad fuel presure regulator.

I would replace pump with a delphi unit.
Do not use a Airtex or aftermarket unless you want to be replacing it 4-5 times.
And check wiring to it.
Then retest running fuel pressure.

Good luck and let us know how it goes.

Good job, it looks like a bad fuel pump.

Just check the relay and grounds too.

I hate changing GM fuel pumps. My Camry has a access panel underneath the rear bench and changing th fuel pump is a snap.

thinking a little more on this last night, I was wondering, if the fuel pump is in the tank which we know to be true, what am I hearing up under the dash when the key is turned on. I know it is directly related to the fuel pump because when it kicks on I hear it and the fuel pressure increases, when it goes off the fuel pressure decreases. I only hear it when the keys is turned on for a few seconds without starting the motor.

I'm still a little hung up on why this only occurs when the temp is above 80

thinking a little more on this last night, I was wondering, if the fuel pump is in the tank which we know to be true, what am I hearing up under the dash when the key is turned on. I know it is directly related to the fuel pump because when it kicks on I hear it and the fuel pressure increases, when it goes off the fuel pressure decreases. I only hear it when the keys is turned on for a few seconds without starting the motor.

I'm still a little hung up on why this only occurs when the temp is above 80

Key on the computer turns the fuel pump relay turns the fuel pump on for a 2 second prime up.
Engine cranking or running the engine computer turns on fuel pump relay.

That is why you should check for 12 volts to fuel pump key on 2 second prime up or engine crankig or running.

If the fuel pump relay fails to turn on fuel pump you will not have fuel pressure or pump running.
If on engine cranking you lose spark on secandary ign the computer will not turn on pump relay.