Ok i have a 94 chevy s10 pickup 4.3 tbi 5 speed 4x4 with about 225000 on the truck. Im having issues with the truck backfiring having no power not being able to hold an rpm and just plain running like crap the truck will idle but only for about a minute
Parts Changed
:fuel filter
:fuel pressure regulator
:cap rotor and wires
I checked the timing chain and the timing chain is good. I even tryed a different distributor and had no change. Im just at the end of my chain trying to figure whats wrong with this thing please help me. Any idea you have just throw it out there thanks to all that help

Ok i have a 94 chevy s10 pickup 4.3 tbi 5 speed 4x4 with about 225000 on the truck. Im having issues with the truck backfiring having no power not being able to hold an rpm and just plain running like crap the truck will idle but only for about a minute
Parts Changed
:fuel filter
:fuel pressure regulator
:cap rotor and wires
I checked the timing chain and the timing chain is good. I even tryed a different distributor and had no change. Im just at the end of my chain trying to figure whats wrong with this thing please help me. Any idea you have just throw it out there thanks to all that help

coil maybe???

im not sure if a 94 has a coil my 93 has a coil

i also had this problem with a 83 s10 and a 82 suburban which was kinda like what your describing and it ended up being the coil had a crack in it. the 83 used to do that when it was damp outside the 82 started doing it for no reason and just swapping stuff around untill the coil fixed it

Some of those had an electric E.G.R. valve,
they tend to get stuck open with small bits
of carbon. They have three ports, Pull the valve
and check the ports.

I agree with Happy.... EGR problems happen all to often and it's easy enough to pull it off and check the valve... you can also take an air hose and try blowing as much carbon out (if that be the problem). I just had that problem a month ago or so. I have 165K on my 4.3 and found almost an 1/8" of carbon in there... check it out! :D

fuel pump.... my brothers did the same thing. had 45psi instead of 65psi.

Definitely fuel pump. Gitcha fuel pressure tester and check it out, or have a shop do it for ya. Easy peasy. The old TBI motors don't have even half the fuel pressure requirements as the later 96+ spfi motors, or the 92-95 CPI motors.

It's a TBI Motor, fuel pressure should be in the 10-15psi range

I'm willing to bet it's a coolant temp sender/ temp sender connector. Check the connector by wiggling it and see if it gets better. You can see what the sender is sending the puter by using a scanner or just buy a new one for $15.

i already had the egr valve off and cleaned every bit of carbon off of it surprisingly it wasnt that bad i havent checked the coil itself ill definetly look at it It is a throttle body motor and 2 weeks before this happened the fuel pump acted like it was going out but could hit the tank and it would work fine again just looking at the injectors doesnt look like it is having any problem getting fuel and the exhaust smells really rich thanks for the advice any other ideas throwem out there

It's a TBI Motor, fuel pressure should be in the 10-15psi range

I'm willing to bet it's a coolant temp sender/ temp sender connector. Check the connector by wiggling it and see if it gets better. You can see what the sender is sending the puter by using a scanner or just buy a new one for $15.

checked the coolant temp sensor already had an issue like that about 2 months before and it was just unplugged but bought a new one cause the plastic busted off the top

2 weeks before this happened the fuel pump acted like it was going out but could hit the tank and it would work fine again

Isn't this where you should start looking? May just be a bad ground, but if this has happened just 2 weeks ago, that's prolly the prob.

checked the coolant temp sensor already had an issue like that about 2 months before and it was just unplugged but bought a new one cause the plastic busted off the top

How did you "check it"?


TBI motors are really picky with grounds also
I had the same problem, turned out the connector was bad, you could stick a test light into the CTS and it would all of a sudden work better.

If it was a bad fuel pump ground I doubt it would run rich...

How did you "check it"?

well, wont matter now, he replaced it with a new one

have you scanned the engine? my was runnin like s and the scanner said egr pintle position not closing. the electronic egr is like 120 bucks but if it has 225k on the motor it probably is that. also the vehicle will not start with 45 psi. mine would start on starting fluid then run fine but you need 65 to start it. so if it starts it is not the fuel pump.

isnt a 94 cpi not tbi or did they make both?

isnt a 94 cpi not tbi or did they make both?

they had both. i have a 94 tbi but it has the vortec bottom end from the factory

the truck still has the old style egr valve that is run on vaccum

Sounds like the fuel pump. Beating on the pump is not a fix, its a temporary solution to a pump that is about to fail permanently. Your pump is like $50, replace it or at least get the fuel pressure tested.

Got any codes?
ABout the only thing the puter doesn't monitor is fuel pressure. If you ahve codes, what are they? No codes is another clue leading to your fuel pressure.

Running like shit could also be from a spark plug wire in teh wrong place, like you got at least two of them mixed up. Check them again.

Running rich would indicate taht your O2 sensor isn't working or your MAP/MAF isn't working right. Got any codes? Both of them are tracked by teh puter.

Sounds like the fuel pump. Beating on the pump is not a fix, its a temporary solution to a pump that is about to fail permanently. Your pump is like $50, replace it or at least get the fuel pressure tested.

Got any codes?
ABout the only thing the puter doesn't monitor is fuel pressure. If you ahve codes, what are they? No codes is another clue leading to your fuel pressure.

Running like shit could also be from a spark plug wire in teh wrong place, like you got at least two of them mixed up. Check them again.

Running rich would indicate taht your O2 sensor isn't working or your MAP/MAF isn't working right. Got any codes? Both of them are tracked by teh puter.
the fuel pump is working fine i took it out fixed the ground problem it did have i havent had a chance to get a scanner on it mainly cause i dont have the money to have a shop pull the codes up the spark plug wires are fine theyve been checked and rechecked the o2 sesor wouldnt have anything to do with what it does on startup and the computer doesnt take any signal from the o2 till the motor is warmmed up MAP sensor is also working correctly even took another one off of a running vehicle to check to be sure and this engine doesnt come with a MAF

use a jumper wire and blink out the codes. google search how to, it's pretty easy to. also you said you changed the cap, rotor, wires. check the plugs too. i've seen them crack or the electrodes burn off. another thing you can do is while the truck is idleing pull one wire at a time from the cap, listen for engine speed to drop. if you pull a wire and no drop then thats the bad cylinder and you need to see whats wrong with it

check your IAC (Idle Air Controller) on your throttle body.

I am not an expert by any means but a buddy was having problems with a 5.3 the other day it would run like crap and die when you put it in gear. He ended up taking it to firestone and all they did was clean carbon out of the IAC and clean out the throttle body some and it runs like a champ now (cost him like 150 bux :eek:)

Especially with that many miles, I would check for carbon build up in/around the throttle body and clean it all out.

Autozone will read the codes for free.

So what did you ever find out about your problen? Mine is doing the samething as your. We done about all same things to our 96 4.3.

So what did you ever find out about your problen? Mine is doing the samething as your. We done about all same things to our 96 4.3.

no i havent pinpointed the exact problem but i have found a few guys with the same problem and there is a control module on the steering colum that helps control the ignition time ive had two guys say that this was the problem with their s10 my only problem is the fact that this module costs around 280 new so ive been searching salvages yards for one nothing for sure yet but its deffinately somthing to look at

This will sound foolish but do a tap test on the PCM. The PCM's will sometimes have a corroded ground inside of them causing idle/running problems.

will give it a try

Did you read any codes? You should be able to get it done for free at the parts store or with a jumper wire.

I'm having the same issue with my 94 cpi blazer. I just got a steal on a 2001 4.3 4x4 s10 so now I want to use the 94 engine for my flat fender.