00 S10 2.2 fuel press check??


trox
10-22-2011, 01:11 PM
I have been thinking my pump was on its way out because when cold, (first start of the day) it always fired up quick but during the hot summer, after that first start it would need to crank for several seconds before catching on. Once started and cleared out, the engine always runs good. I replaced the fuel filter when I put a new engine in 3000 miles ago. I try to wait for the pump to prime on every start but the other night I went for a couple beers and when I came out to leave, it tried to start but didn't quite catch. After that, it would only crank and almost fire but wouldn't catch and run. I may not have waited for the pump to finish priming. This is the first time its left me stranded. Had to leave it overnight and came back the next day and it fired right up as usual in the morning. I have a pressure gauge on it now and I get the following pressures cuz I know MT will ask.
-before the filter, capped off line: 74psi KOEOff, press drops to 60 after 10 seconds
-through filter w/system intact: 48psi KOEOff for 3-4 seconds, 40 with engine running, 39 after 30 minutes running
-after shut down, pressure drops to 30, drops to 18 after 3 minutes
-overnight I have 10 psi on the system
I'm not sure how to check the regulator, could it be the cause of my hard to start issue after its been running? The hard to start has gotten better since the weather has cooled off. Its like a cold start hot start issue but I don'tknow if the S10 has this feature.
Ant suggestions? --Also my fuel level indicator freaks out from empty (low fuel lt) to full and thats an issue I can live with before spending 275 on a pump assembly if I don't need a pump yet.

inafogg
10-22-2011, 02:46 PM
I have been thinking my pump was on its way out because when cold, (first start of the day) it always fired up quick but during the hot summer, after that first start it would need to crank for several seconds before catching on. Once started and cleared out, the engine always runs good. I replaced the fuel filter when I put a new engine in 3000 miles ago. I try to wait for the pump to prime on every start but the other night I went for a couple beers and when I came out to leave, it tried to start but didn't quite catch. After that, it would only crank and almost fire but wouldn't catch and run. I may not have waited for the pump to finish priming. This is the first time its left me stranded. Had to leave it overnight and came back the next day and it fired right up as usual in the morning. I have a pressure gauge on it now and I get the following pressures cuz I know MT will ask.
-before the filter, capped off line: 74psi KOEOff, press drops to 60 after 10 seconds
-through filter w/system intact: 48psi KOEOff for 3-4 seconds, 40 with engine running, 39 after 30 minutes running
-after shut down, pressure drops to 30, drops to 18 after 3 minutes
-overnight I have 10 psi on the system
I'm not sure how to check the regulator, could it be the cause of my hard to start issue after its been running? The hard to start has gotten better since the weather has cooled off. Its like a cold start hot start issue but I don'tknow if the S10 has this feature.
Ant suggestions? --Also my fuel level indicator freaks out from empty (low fuel lt) to full and thats an issue I can live with before spending 275 on a pump assembly if I don't need a pump yet.


not sure what the fp psi is susposed to to be,but with engine running
disconecting the f/reg vacuum should increase pressure 7-10 psi.also make
sure you have vacuum.your initial pressure 74 psi sounds ok also if you have'nt i'd replace f/filter

trox
10-22-2011, 04:03 PM
I just started to check the pressure with the regulator vacuum line on and off. I'm assuming the line to remove is the larger vacuum line gong onto the top of the throttle body. The pressure remained the same with it running and removed, vacuum line on or off. I have very little vacuum at the port on the throttle body at idle, I can goose the throttle and get 7-10 hg. My fuel pressure will increase 5-6 psi when I goose the throttle but it returns to 41. If I bring throttle up slowly, pressure remains the same at 41. If I follow the line back it goes down to the side of the block to a round component I assume is the regulator. If this is it and I need t replace the regulator it looks like a P.I.TA. Let me know if I'm doing this check right. Shoild I have much vacuum at idle?

MT-2500
10-23-2011, 04:42 AM
I just started to check the pressure with the regulator vacuum line on and off. I'm assuming the line to remove is the larger vacuum line gong onto the top of the throttle body. The pressure remained the same with it running and removed, vacuum line on or off. I have very little vacuum at the port on the throttle body at idle, I can goose the throttle and get 7-10 hg. My fuel pressure will increase 5-6 psi when I goose the throttle but it returns to 41. If I bring throttle up slowly, pressure remains the same at 41. If I follow the line back it goes down to the side of the block to a round component I assume is the regulator. If this is it and I need t replace the regulator it looks like a P.I.TA. Let me know if I'm doing this check right. Shoild I have much vacuum at idle?

Fuel pressure looks good.
But vacumn not so good.
Fuel pressure specs is 41/47.
Key on engine off after fuel pump primes up or engine cranking you should have 45-47 lbs pressure.
On a cold prime up you may have to flip key off /on several times to get full prime up.
Or on engine cranking crank several turns or times to get full prime up.
Engine idle full vacumn on pressure regulator 41-42.
Full load on engine it should jump to 46-47.
Also pull vacumn hose off of pressure regulator and chec for gas in line.
And check vacumn on that hose engine running.

We need a direct engine vacumn reading at idle and at 2K rpm cold and hot.

You should have 18-21 in. vacumn at idle and should not drop lowerat 2K rpm.
Engine running at idle you should see around 42-43 depending on engine vacumn and load.
Double check fuel pressure readings agaist specs posted.
Post back pressure readings and vacumn readings.

trox
10-23-2011, 10:17 AM
The pressure readings look like what I have been seeing. The vacuum I have at the top of the throttle body (not the hose end) at idle hardly moves my vacuum test gauge. If you say I need 18-21 inches at idle, what could be the cause of that? The motor is a re-man from a reputable engine supplier that runs well. If I pull a vacuum on the line to the regulator I should see a drop in pressure to 41-42 but I'm at 41 at idle now. I'll check one of the other vacuum ports on the throttle body next. There must be some vacuum somewhere. Another question though, Should some pressure remain on the system? because mine drops to zero over 3-4 hours.

trox
10-23-2011, 12:58 PM
Just had another look at things and I've been checking vacuum at the wrong port. After looking at what the regulator looks like on line, the small line that goes under the intake plenum to the back is where I find the regulator, not under on the side of the block by the distributor and NOT the larger port on top of the throttle body. Anyway..., my idle vacuum is about 17 plus or minus for old gauge error. It spikes and returns back to 17 at 2000rpm. I notice this morning there was still 10-11 psi on the fuel pressure gauge. Other times I've come out to find it at 0 psi after 3-4 hours. Should there always be some pressure on the system? Fuel injectors bleeding the pressure off or a check valve in the pump? If I do my first check again before the filter with the outlet line capped off and check pump pressure, should it hold that pressure or some pressure? Since I've started investigating with the fuel gauge installed, it's started pretty good every check I make. OK...I just put the pressure gauge direct to the pump and capped it off. I get 76 psi when I hit the key, then it drops off to 60psi after the pump stops the prime cycle. I turn the key off and I get a steady drop to about 40 after 2 minutes. I'll leave the gauge on for a few hours to see where it goes from there.

MT-2500
10-23-2011, 01:21 PM
Just had another look at things and I've been checking vacuum at the wrong port. After looking at what the regulator looks like on line, the small line that goes under the intake plenum to the back is where I find the regulator, not under on the side of the block by the distributor and NOT the larger port on top of the throttle body. Anyway..., my idle vacuum is about 17 plus or minus for old gauge error. It spikes and returns back to 17 at 2000rpm. I notice this morning there was still 10-11 psi on the fuel pressure gauge. Other times I've come out to find it at 0 psi after 3-4 hours. Should there always be some pressure on the system? Fuel injectors bleeding the pressure off or a check valve in the pump? If I do my first check again before the filter with the outlet line capped off and check pump pressure, should it hold that pressure or some pressure? Since I've started investigating with the fuel gauge installed, it's started pretty good every check I make.

3-4 hr pressure drop is normal.

With vacumn hose off of pressure regulator pressure should jumpup to 46-47 lbs pressure.

For checking engine vacumn find a vacumn port direct into intake.
There should be several places.
Where heater control vacumn line go to engine or vacumn line to brake booster or line to pressure regulator or pcv valve.

Does engine run at full power on road?

VACUMN READING IS A LITTLE LOW.
Engine at 2K -2.5K it should be jumping up over idle vacumn.

Check for restricted exhaust.
Pull 02 sensor or drop exhaust pipefor test.

trox
10-23-2011, 03:13 PM
My pump pressure is still 28 after 1.5 hours. You say it's OK to drop to 0 overnight? I have a complete new exhaust with a header. My power at top end is good. The only thing confusing me at the moment is why the pressure drops to 0 sometimes after 4 hours and this morning for instance, it was at 10 before touching it. That was with the gauge on system complete, now I have the pump line capped. The one thing that is encouraging is the pump pressure has primed up to specs every time. (probably 30 times so far since Friday) If the pump primes up good (as long as I wait before cranking) you would think I'd be OK but I know after a 2 hour wait, it'll take a 4 to 6 second crank to start (even after waiting for the prime) and then it barely catches on, I clear it out and it runs fine.

MT-2500
10-23-2011, 04:13 PM
My pump pressure is still 28 after 1.5 hours. You say it's OK to drop to 0 overnight? I have a complete new exhaust with a header. My power at top end is good. The only thing confusing me at the moment is why the pressure drops to 0 sometimes after 4 hours and this morning for instance, it was at 10 before touching it. That was with the gauge on system complete, now I have the pump line capped. The one thing that is encouraging is the pump pressure has primed up to specs every time. (probably 30 times so far since Friday) If the pump primes up good (as long as I wait before cranking) you would think I'd be OK but I know after a 2 hour wait, it'll take a 4 to 6 second crank to start (even after waiting for the prime) and then it barely catches on, I clear it out and it runs fine.

Slow pressure drop engine of is no problem.
Overnight or after a couple of hrs. no problem.

When pressure bleeds off like overnight it may tke more that on key on flip/2 second fuel pump prime up to get back thefuel system back up to full pressure.

Get the fuel pressure gauge on it after a 2 hr wait and check the fuel pressure when it starts cranking.
Watch for what pressure it has on start to crank and after 4-6 seconds.

Also check the fuel pressure vacumn line to fuel pressure regulator for gas in it.

Another fuel system test is to give it a squirt of carb cleaner.

How is your tune up?
Good plugs and fuel and air filter and spark?
How many miles on it?
Any check engine lights or codes?

MT-2500
10-23-2011, 04:17 PM
Is only after a 2 hr wait the only time you have a slow start?
Good start after a hot soak of 10-20 minutes?

When it has a slow start does it idle rough or have a engine miss after starting?
Any black or blue smoke out tail pipe?

trox
10-23-2011, 05:25 PM
OK, pressure on the capped off pump after sitting for 2.5 hours was still 25psi. It definitely holds better when capped off for what that's worth. I put the system back together with the gauge slaved in. After 3 primes (to clear air out) the pressure charged to 47 then dropped to 41, on crank to start it was 47 during crank but and it lit off quick. Pressure drops to 41 at idle. So it is running during the crank cycle.
Answers to your questions:
--no fuel in the vacuum line to regulator--
Is only after a 2 hr wait the only time you have a slow start? ---yes---
Good start after a hot soak of 10-20 minutes?---yes---

When it has a slow start does it idle rough or have a engine miss after starting?--not after clearing it wit a couple pedals---
Any black or blue smoke out tail pipe?---nope
How is your tune up?--all new stuff, just put re-manned engine in 3K ago---
Good plugs and fuel and air filter and spark?--yep---
How many miles on it?---3k---
Any check engine lights or codes?---yes, had an O2 sensor after cat code, I replaced the sensor Friday while under the truck. could the O2 sensor cause the hot slow to start, cold good start? The other code I had was the fuel qty system code that I figure was from the gauge going from E to F every 5-10 miles. I can't remember the code numbers but the reader told me the cause for each code.
If there is chance the O2 sensor fixed this I'll pull the pressure tester and drive on. Either way, I don't think I'm any worse off than I was, it just pi$$ed me off when it wouldn't start for me after coming out from a meal in town. It's never left me out in the cold like that so I'm testing the heck out of it.
Thanks for listening while I rant.

MT-2500
10-23-2011, 05:37 PM
OK, pressure on the capped off pump after sitting for 2.5 hours was still 25psi. It definitely holds better when capped off for what that's worth. I put the system back together with the gauge slaved in. After 3 primes (to clear air out) the pressure charged to 47 then dropped to 41, on crank to start it was 47 during crank but and it lit off quick. Pressure drops to 41 at idle. So it is running during the crank cycle.
Answers to your questions:
--no fuel in the vacuum line to regulator--
Is only after a 2 hr wait the only time you have a slow start? ---yes---
Good start after a hot soak of 10-20 minutes?---yes---

When it has a slow start does it idle rough or have a engine miss after starting?--not after clearing it wit a couple pedals---
Any black or blue smoke out tail pipe?---nope
How is your tune up?--all new stuff, just put re-manned engine in 3K ago---
Good plugs and fuel and air filter and spark?--yep---
How many miles on it?---3k---
Any check engine lights or codes?---yes, had an O2 sensor after cat code, I replaced the sensor Friday while under the truck. could the O2 sensor cause the hot slow to start, cold good start? The other code I had was the fuel qty system code that I figure was from the gauge going from E to F every 5-10 miles. I can't remember the code numbers but the reader told me the cause for each code.
If there is chance the O2 sensor fixed this I'll pull the pressure tester and drive on. Either way, I don't think I'm any worse off than I was, it just pi$$ed me off when it wouldn't start for me after coming out from a meal in town. It's never left me out in the cold like that so I'm testing the heck out of it.
Thanks for listening while I rant.

Yes o2 sensors can cause hard start.
Tempt sensors and tps sensors and map and air flow can affect it to.
Also EGR valve stiching open.
Everything has to work to gether.
Repair and clear any codes and recheck for codes returning.
Post back any and all code no.

trox
10-23-2011, 07:07 PM
I put her all back together. It started fine again after removing the gauge setup. I cleared the codes and we'll see what happens. I was getting 23 MPG so that might change with a little luck too. That's really why I changed out the O2 sensor, I wasn't thinking of it causing my start problem. I'll post back in a week or two after filling up with gas to see how my MPG does.
Thanks MT

trox
10-28-2011, 09:32 PM
In my last post, I had checked the fuel pump pressure with a gauge and all was good. MT asked if I had any codes and I did. I had P0420 so I replaced the O2 sensor and after the second day, I got it back again. When reading for the code this time I cleared it off and it is off now. I confess at this point that I removed the CAT and replaced it with a straight pipe when I replaced the engine with new 3K ago. I have all new plugs and wires, filter, both O2 sensors are new.

Well I'm back to where I was last Friday only this time I'm at home and not stranded in town. After having the fuel pump tester on it all weekend and not seeing an issue and not duplicating my problem, I could tell it it still doesn't start as well in the afternoon as it does in the morning on Monday. I've driven it to work M-T-W this week and I decided to check the coils after getting home since it tends to not start so well after driving a while. They checked out according to the manual as far as resistance goes both hot and cold. Now after putting the coils back on and starting it up, it fired up quick (as usual on the first start of the day). Then I tried to start it back up (after about 15 minutes) to go out in it and it's not starting. It gets real close but just not quite enough to let off the key. I checked the spark of 1 plug and it looks good. There is fuel on that plug from trying to start it. I think it'll fire up in the morning but I'll post back and let you know. At this point, I can't leave the house because it may be getting worse which is a good thing I guess. Ant ideas from anybody?

MT-2500
10-29-2011, 04:43 AM
In my last post, I had checked the fuel pump pressure with a gauge and all was good. MT asked if I had any codes and I did. I had P0420 so I replaced the O2 sensor and after the second day, I got it back again. When reading for the code this time I cleared it off and it is off now. I confess at this point that I removed the CAT and replaced it with a straight pipe when I replaced the engine with new 3K ago. I have all new plugs and wires, filter, both O2 sensors are new.

Well I'm back to where I was last Friday only this time I'm at home and not stranded in town. After having the fuel pump tester on it all weekend and not seeing an issue and not duplicating my problem, I could tell it it still doesn't start as well in the afternoon as it does in the morning on Monday. I've driven it to work M-T-W this week and I decided to check the coils after getting home since it tends to not start so well after driving a while. They checked out according to the manual as far as resistance goes both hot and cold. Now after putting the coils back on and starting it up, it fired up quick (as usual on the first start of the day). Then I tried to start it back up (after about 15 minutes) to go out in it and it's not starting. It gets real close but just not quite enough to let off the key. I checked the spark of 1 plug and it looks good. There is fuel on that plug from trying to start it. I think it'll fire up in the morning but I'll post back and let you know. At this point, I can't leave the house because it may be getting worse which is a good thing I guess. Ant ideas from anybody?

Keep on testing and checking.

You need to check spark to all plugs.

Fuel on plug is not good.
Removing cat is not good.
Make sure all tempt sensors and TPS and Map and MAF sensors are good.
Any one of them out of specs or bad can give a hard or no start.
As said everything has to work together.
On coil test the best test is for good hot blue spark when cold and hot.
To check for fuel delivery problems a good shot of carb spray helps.

trox
11-15-2011, 04:44 PM
Well I've had the truck sitting in the garage for the last 2 weeks waiting for it to not start but every time I reached in through the window to start it it fires right up. Today my sons car was messed up so I had to use the truck. Sure enough, it fired right up this morning but I come out this afternoon to go home from work and the little bastard won't start. I had ether on hand to give it a shot and it don't help. It cranks good and almost starts but just don't won't quite catch. I don't have an extra hand to try shooting it in while cranking but I don't think it'll help. I think it's a sensor but don't know which one to replace first. Both O2 sensors are new. When the truck starts it runs great. I've looked at the MAP sensor and it looks OK. How do I test the MAP and MAF and TPS and water temp sensors? Are there ohm values for these? No check engine light since replacing the rear O2 sensor recently. That was my only code before.
If anybody has been throught this before, please let me know what you have found. I think I'll start a new thread called 2.2 won't start since I've checked the fuel pressure and it seems good.

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