Perfomance problem?

Ill have to check it tomorrow night. Need a buddy to turn it over and also need the fuel pressure guage. Till then...

Also...I bought a TBI fuel guage...does that matter? It fit on the pressure relief fitting. The guy at autozone said to get it because it could be used for engines with more pressure. The alternative was a fuel guage for 3 bucks less that wasnt labeled TBI. I thought the 3 bucks were worth it, unless it doesnt work on my truck!! LOL

The weird thing is that it started right up last night ( tried it 5 times at least) and now this is happening. Had spark and fuel last night, was running awesome!

Also, charge your battery.

Ill have to check it tomorrow night. Need a buddy to turn it over and also need the fuel pressure guage. Till then...


I checked for spark and fuel pressure by hand. There is spark and pressure, but i wonder if there is enough pressure. I will check tomorrow night (wed), as i will get pressure guage back tomorrow am. My friend who owns a garage thinks its the fuel pump. He says that with the system leaking all over it didnt have to keep the pressure at a high pressure. When I drove it home I caught it by suprise and it did ok. And now with it being old and stressed it cant create the 50 to 60 pounds of pressure to fire the truck back up. I picture an old fat guy having to run and having a heart attack! lol

It could be that or your battery is not supplying the proper voltage and current to get the proper pressure out of the pump.

As I said before, charge the battery, and see what the coltage reading is while running and while not running.

It all could be just a battery.

It could be that or your battery is not supplying the proper voltage and current to get the proper pressure out of the pump.

As I said before, charge the battery, and see what the coltage reading is while running and while not running.

It all could be just a battery.

I have that guage (battery) in the dash. Always fine except its going down to around 10 since Ive been trying to start it. Really strong cranking still.

EDIT...

And remember this all started after it ran fine coming home. Didnt touch it and when I awoke........no go.

Change your battery!

Change your battery!

ok ok damn lol

ok ok damn lol

That is not me, he is impersonating me and he will be delt with shortly.

His IP address is currently logged.

That is not me, he is impersonating me and he will be delt with shortly.

His IP address is currently logged.
cool

I just checked the fuel pressure. Ranged from 44 to 49. Checked it three times.

Seriously... Fix the problem ASAP -- within the next 25 miles or sooner. Get the idea!

Also, I had a 95 Jimmy with a bad CAT.... The codes said the back 02 sensor failed and the EGR Pintle Value stuck. Once I replaced both my engine ran smoother and had better acceleration. I did not replace the CAT. Then I sold it. However, I don't think the CAT going bad is a performance or other concern mechanically. Maybe someone else can comment on that?

I just checked the fuel pressure. Ranged from 44 to 49. Checked it three times.


WAYYYYYYYYYYYYYYYY TOOOOOOOOOOOO LOW... should be 56-60 to start and 61-65 at run

Yeah....so it points to the fuel pump right? I kinda need a over 50 percent kinda reply as this is my only vehicle, Im stuck without any tools and to borrow them usually take a day. I have a couple of hundred buck I borrowed to get it fixed and would love to call my buddy to fix it tomorrow. 150 plus the pump to replace it. I dont want to do it since I dont have any tools handy and if I screw somrthing up I dont have any Idiot money. :)

Pull the upper plenum first and check for signs of washing. It could be your CPI and/or nut kit. Do that before going through hell dropping the tank.

Pull the upper plenum first and check for signs of washing. It could be your CPI and/or nut kit. Do that before going through hell dropping the tank.


I cant smell any gas at all...none.

That doesn't mean anything, PULL THE UPPER PLENUM AND INSPECT for washing...

That doesn't mean anything, PULL THE UPPER PLENUM AND INSPECT for washing...


I dont have any tools here. I mean I stuck my nose in the intake hole with the damper opened and didnt smell gas. I got as close as humanly possible without taking off the upper intake manifold. Absolutely no gas smell. I was sniffin 10 inches of free air from inside.

I am stuck in my house, truck out back, and gettin rides to and from work for the last three days and probably the next three. I have 200 bucks left and cant wait for the tax man to shit. I dont have a volt meter to check voltage and it took me 2 days to get the pressure guage.

I appreciate all of the help, but the resources are running low and I need this fixed.

Again ...I have no tools and need your educated guesses and opinions as to what to do. Im leaning towards getting it towed to my buddys shop and paying him. Tomorrow. AM

Yeah....so it points to the fuel pump right? I kinda need a over 50 percent kinda reply as this is my only vehicle, Im stuck without any tools and to borrow them usually take a day. I have a couple of hundred buck I borrowed to get it fixed and would love to call my buddy to fix it tomorrow. 150 plus the pump to replace it. I dont want to do it since I dont have any tools handy and if I screw somrthing up I dont have any Idiot money. :)

Before you take anything apart, TAKE A VOLTMETER and test the battery voltage with the engine off and with the engine running.

I am not talking about the gauge in the dash, USE A VOLTMETER.

If you don't have a v-meter (like most of us) maybe you do have a "known" good battery you can use....?

Or maybe Blazer LT can verify this alternative approach: Use a jump to another car (while it's running) to see if this creates a different condition? (Just trying to help... I'm not an experienced mechanic.)

BlazerLT is.... So follow his lead not mine. Good luck.

Hehe, I'm not a mechanic either, just very experienced seeing I have fixed trucks since I was 10.

Battery is so easy to check and doesn't cost anything.

Hi, I'm new to the forums, I saw this interesting thread.... I'm having the same problem with a truck i recently purchased. It's a 1985 frame, 1986 southern body, and a 1989 chevy blazer 4.3l TBI Engine. This engine has around 100,000miles. It runs pretty good, but my fuel mileage is around 4-8MPG. Right away I knew something wasn't right. It has a 3 inch body lift and 31 inch tires. Still this can not be? Well it was snowing here recently and I looked at the snow where I had parked and under the exhaust I noticed it was black sootie (sp) looking snow. I thought... It's running rich right? So I had a friend rev it up a little bit and noticed it was puffing black smoke... This tells me the motor is running rich. I've looked at the Injectors and they are spraying a fine mist not dripping. This tells me I have other problems... The truck runs very good when revved but I've noticed a few things...

Rough Idle when I first start it, or let it rev down....

4-8MPG, The egr is not hooked up due to the wiring harness having 4 prongs instead of the 2 on the egr (it might be the other way around, not sure)

This truck was put together from scratch so it's hard to tell... Ya know...

I have put a new cap and Ignition rotor on the truck.. This did not help..

So I did a little research and it brought me here... My question to you is...

What parts do I need to replace and what are they exactly called?

Any help would be appreciated, Thanks very much guys... You guys seem to be great at helping people.

Let me know, Thanks again... Peter

You did use the 1989 computer right?

Remove the timing wire from the computer.

Time the vehicel to zero with a timing gun.

Reconnect wire.

Your timing is really retarded , it is that or you need a tuneup badly.

Hehe, I'm not a mechanic either, just very experienced seeing I have fixed trucks since I was 10.

Battery is so easy to check and doesn't cost anything.


Fine... I agree, but would a simple jump from another car work if that is easier and faster? You are trying to rule out the possibility of a low battery as the source of the problem, right? I just thought this would be an alternative approach and I wanted some verification of that.

Fine... I agree, but would a simple jump from another car work if that is easier and faster? You are trying to rule out the possibility of a low battery as the source of the problem, right? I just thought this would be an alternative approach and I wanted some verification of that.


I am not sure of the computer, but I know it is the right one. The guy before me is actually my friend. I know he would try to do everything right. He said it was 6,000 to build the truck. The timing is fine, The motor runs like a champ. He said he messed with the timing numerous times becuase it is slow to start (it cranks a few times first) I'm thinking that the problem is my fuel system.

A friend told me to pull the vacum line off the Fuel Pressure Regulator (FPR) and see if it is shooting gas when im cranking the engine or while it is running. If this is the case I have reason to believe it is the FPR. I will do this tomorrow and ask my friend what computer this is.

Thanks for your help.

Let's not ASSUME anything.

Remove the timing wire, tire the vehicle and replug in the wire to the computer.

Assumption is the mother of all automotive screwups.

I will time the truck tomorrow. Just so I can rule that out. Another ?... My EGR, Not hooked up and all... Could the computer try to compensate for this by richening the mixture?

Thanks

Also lol, Any ideas for a good sounding exhaust, or a good horsepower adding exhaust... Say a nice deep rumble or something? Thanks lol....

Let's not ASSUME anything.

Remove the timing wire, tire the vehicle and replug in the wire to the computer.

Assumption is the mother of all automotive screwups.

For my own knowledge, where is the timing wire located? This sounds like a good idea to check on my 97 blazer. I trying to rule out all options on why I may not be getting optimum gas mileage.

Your 97 is computer controlled with a locked distributor and can't be adjusted. In order to change the timing you would have to tweak it through the ECM. The timing wire issue only applies from 91-95 (95 version with the top post mount dist. Side post style is locked like 96 to current)

Your 97 is computer controlled with a locked distributor and can't be adjusted. In order to change the timing you would have to tweak it through the ECM. The timing wire issue only applies from 91-95 (95 version with the top post mount dist. Side post style is locked like 96 to current)


So you are saying on all '97 (and I presume newer models) the timing will always be accurate? Interesting.

Can you buy modules to change the perfomance curve?

... And is the reason why some Blazer's are getting better gas milage than other Blazers related to a less than perfect ECM?

I'm just streatching for clues as to why my gas milage is not as good as yours???

The '85 and '86 were carburated 2.8's, not TBI's so it is at least a TBI 4.3 computer, or it wouldn't run at all. With a disconnected EGR, you should be getting a SES light, DTC code 32 to be exact. It won't cause a rich exhaust, but its certinly not helping. If its running that rich, you should also be getting a DTC code 45 - rich exhaust. If you 02 sensor is working right, it will bring that code up. Check for codes first and see what you get.

The '85 and '86 were carburated 2.8's, not TBI's so it is at least a TBI 4.3 computer, or it wouldn't run at all. With a disconnected EGR, you should be getting a SES light, DTC code 32 to be exact. It won't cause a rich exhaust, but its certinly not helping. If its running that rich, you should also be getting a DTC code 45 - rich exhaust. If you 02 sensor is working right, it will bring that code up. Check for codes first and see what you get.


I will do that tonite. It has an aftermarket SES Light underneath of the dash. I know the kid said it is getting an EGR error. I will check with a paper clip tonite.

I will match it to the codes on autozone and see what I get.

Thanks... Peter

I will time the truck tomorrow. Just so I can rule that out. Another ?... My EGR, Not hooked up and all... Could the computer try to compensate for this by richening the mixture?

Thanks

Yes, the EGR could indeed be causing this a bit. The EGR gas allowed back into the system is there to lower combustion temperatures and inhibit detonation.

Without it, you will be detonating and your knock sensors could be retarding your timing to compensate.

Best to get that fixed.

So you are saying on all '97 (and I presume newer models) the timing will always be accurate? Interesting.

Can you buy modules to change the perfomance curve?

... And is the reason why some Blazer's are getting better gas milage than other Blazers related to a less than perfect ECM?

I'm just streatching for clues as to why my gas milage is not as good as yours???

Your system is completely computer managed.

The computer at all time is advancing the time to the max your engine can handle with the fuel you are using.

CPI Unit for $199. if I knew that this was needed...I would have started with...CPI and Fuel Pressure Regulator...and Nut Kit

This forum is a Blessing to find out about these problems...and the way the 4.3 V6 runs after the replacement...is great and it now gets about 20mpg highway...which is very important to me...

Remove Clean and Replace the ERG...search this thread to find out about ERG valves...and gaskets...

Wishing You all Well...Do good...MJohn

That doesn't mean anything, PULL THE UPPER PLENUM AND INSPECT for washing...

93 4.3l W CPI

I am in the process of replacing my CPI (waiting on ebay shipment) and having a hard time talking w/ a GMC parts guy who knows how to get the complete "nut kit" or "internal line kit", I think the nut kit # is 17112705

The left side of my plenum was def washed nearly clean. The right beautifully sooty. I used some gasket cleaner to clean the upper plenum cavities fairly well. Can you tell me if I should be more thorough or meticulous in cleaning the plenum cavities?
How about the plenum where the CPI sits - should I wipe this down, try to get as much soot out? w/ gasket remover, or gas, or...?

I accidently replaced the EGR, TPS, and fuel filter - so this Jimmy ought to operate pretty damn good once the CPI and nut kit go in! It better.

Im thinking of going with a carb on mine... I just posten in the Cehvy -> S10 forum about it... Wonder if you could help?

Im thinking of going with a carb on mine... I just posten in the Cehvy -> S10 forum about it... Wonder if you could help?

Don't go there, the injection system wrks perfectly if properly maintained and is way more efficient than any carb.

Man...10 days later. no vehicle...ugh.

Fuel pump was the problem. $305.00 parts and labor.

The shifting is tight (TIGHT!) but becoming more responsive.

Vroom vroom!

So now, its been a week and the transmission is still really tight. I have to coax it into third and overdrive (if it can find it). Very high rpms to get it to shift while accelerating. Shouldnt this have corrected itself by now? I mean its not that bad but annoying since the engine is running like new.

I believe you have the vacuum controlled transmission right?

Im thinkin computer