1988 Chevy S-10 Need help with 4.3 V6 TBI. Please

Tiny
MRDONNIE
  • MEMBER
  • 1988 CHEVROLET S-10
Engine Performance problem
1988 Chevy S-10 6 cyl Two Wheel Drive Automatic 230k miles

I was trying to get help on another forum and didnt get any replies so here is how it goes so far.

Here is my issue. I bought a 88 s10 blazer 2wd with the 4.3L v6. I got the blazer fairly cheap because the guy wasnt mechanically inclined and didnt want to fool with it.

Anyhow, it starts only when you hold the pedal down. Once it does start it has a strong fuel odor and the ground is black from all of the carbon coming out of the tail pipe.

I replaced the coolant temp sensor and rebuilt the fuel pressure regulator. Still the same issue. Today I took it to a shop I deal with from time to time and my buddy put a computer on it. Only code it came back with was MAP SENSOR or high voltage. I replaced the map sensor and it still has the same issue. I have checked the EGR valve by pushing in on the diaphram and best I can tell it is fine. The truck will not run for very good with both injectors plugged because they are spraying so much fuel. With 1 injector, you can get it to putt down the street.

My next step is to just replace the computer, but I wanted to see if someone could shed some light on this issue or perhaps someone that has been through the same thing.


Latest progress:

Ok, I'm back on this project now that the holidays are over. After testing voltages and hooking a computer up to the blazer, I was left with the computer being bad. I put a new computer in today and the car started up and ran horrible for a couple mins and then cleared up. I turned it off for a couple minutes and tried to restart and nothing. I replaced all of the plugs using A/C delco. Once again, started up and ran fine. It would even sit there and purr like a kitten. This didnt last long and it would try and stall out, and then clear up and run fine and then repeat the cycle. I was able to drive it home from the shop about 10 mins away and it ran good with the exception of the pinging and valve clatter. Not sure if it might have some water in the tank or not. I got home, turned it off and let it sit for about a hour. Went back outside to start it up, and would not start unless I held the pedal down. I'm really not sure what direction to go at this point. Would the IAC cause this and OR the EGR valve?

Right after I put the new computer in, the truck started up and ran fine. It sat there and idled for about 10 mins with no issues. Today, I pulled all the plugs out and cleaned them, fired the truck back up and the injectors were once again dumping fuel. Just cranking the motor the injectors were dumping fuel like crazy. Keep in mind it did not do this after I put the new computer in at first, but it did the exact same thing with the old computer in. I had them order me another one and will pick it up in the morning. I am really confused at this point and I hope it was just a faulty computer.

Today's progress:

I put the new computer in and still the same. It will idle somewhat decent on 1 injector but is still dumping fuel. I ran the truck about 5 mins or so and could smell something funny and then seen smoke coming from underneath the truck. I looked underneath and it was REAL hot from the converter back. First time it's done this. I hope the converter is not bad now because the whole exhaust system was replaced last year.

Tonight I checked the map sensor using a voltmeter and a vacuum pump and it seems to be fine pressure and voltage wise. I have pulled the EGR off yet but I did apply pressure to it with the vacuum pump and I could see the diaphragm open and close and it seemed like it was moving pretty smooth.

Far as IAC, I could visually see the pintle moving in and out when I would bump the throttle. I havent checked the TPS yet, I will do that tomorrow.

Sorry for the long post, but I figured the more I could explain what I have done, the more it would help someone to be able to help me.
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Wednesday, January 20th, 2010 AT 10:14 PM

2 Replies

Tiny
TONY_RAY
  • MEMBER
It sounds like a tough one, but you need to check the fuel pressure to see if the pressure is within range. If pressure is ok, then you need to measure the injector voltage to see if they are within range. Now, if this is ok, you may have had too much fuel pressure in the injectors and they have damaged the nozzles. Dont overlook the pressure regulator, as you had said that you rebuilt it, this can be very overlooked as the problem because you believe the regulator is functioning properly. One last thing, check the O2 sensor. The O2 could be the wrong part or is not operating properly because the signal from it tells the computer how to adjust the air/fuel mixture.I hope this is helpful to you, but I really believe the regulator, injectors, or O2 is the answer.
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Thursday, January 21st, 2010 AT 7:11 AM
Tiny
MRDONNIE
  • MEMBER
I doubt it's the regulator because even after being rebuilt, it was still doing the same thing. Also, after putting the new computer in, it would start up and run fine with the exception of a irratic idle that would come and go, but it sat there for a good while and never loaded up and then about a hour later, it was back to the same ol thing.

Also, as of today I am not getting any codes kicked back. I jumped the A and B terminal and I am getting the code 12 which means the light is working, but no further codes are coming back.
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Thursday, January 21st, 2010 AT 4:41 PM

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