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Chevy S10 - GMC S15 and Sonoma Engine and Underhood Problems



  • hoodlatchhoodlatch Mid-westPosts: 255
    Your might try testing the fuel pressure with a gage to make sure your fuel pump is OK. :)
  • gonogogonogo Posts: 879
    Are you using after market modules, try a GM one, I know it will be more but better quality.
  • czbillczbill Posts: 2
    Thanks for the suggestions. I am sure the fuel pump is working, I have already verified lack of both spark and fuel injection when this problem occurs.

    No, I have not been using GM modules, although the last one was a standard, which was known as a good brand in the past. I will try a GM ($$) module.
  • skohanskskohansk Posts: 3
    Bought a Ext 1991 Sonoma 4.3L 4x4 last year with 47k on the motor and tranny. Starts up great, sounds great, drives great, but the thing has no balls. Low end is powerfull especially in 4wd but to have the power that a 4.3 should on the street, i'm at a loss. Any idea's?
  • gonogogonogo Posts: 879
    Sorry for late reply, been away. I would check for a plugged cat converter.
  • hoodlatchhoodlatch Mid-westPosts: 255
    A plugged cat converter makes it feel like your pulling an anchor. I have a 92 4.3z. Once I had a hidden vacuum leak that caused it to run like it was on Tylenol PM. After I corrected the leak (a cracked plastic fitting), it ran great. Good luck :)
  • Still hoping that someone can give me some ideas...
  • hoodlatchhoodlatch Mid-westPosts: 255
    Lone wolf - I’m assuming you have a four cylinder, stick shift. Sounds like you’ve already spent a ton of money on new parts and labor. We've all been there and I understand the frustration.

    Your symptoms sound just the reverse of most problematic engines. My experience with faulty primary or secondary ignition components have been that it acts up the most under load. Same with dirty fuel injector. Ordinarily though, when you have those types of problems, it smooths out to some degree when you let up on the gas.

    Is it possible it’s got a faulty fuel pressure regulator?

    Keep the faith. :)
  • Thanks for the reply. I'll check on the FPR and see what turns up. Now, personally I don't know where the FPR is located. Is it part of the Fuel Sending Unit? Because I've had that replaced already.
  • goracingoracin Posts: 2
    I have a 1997 S-10 with a 4.3 that misses -- It was diagnosed with a bad timing chain which was replaced but was mis-diagnosed -- All marks were right on but it misses at 35 m.p.h. on up -- I have had it scanned and it is showing misfire codes on all cylinders and the service engine light is on. I am thinking it could be a Base Timing issue or a camshaft sensor -- The crank sensor was replaced which I think was the root cause of the original problem. My question is how can Base Timing be checked and can it be adjusted?
  • hoodlatchhoodlatch Mid-westPosts: 255
    My repair manual doesn't cover your truck but I'm sure it isn't in the gas tank like your fuel pump and sending unit. After looking at pictures of it on the web sites of AutoZone and Advance Auto Parts, I would guess it’s under the hood. I’ve seen the same regulator under the hood of other GM cars also. Trace out your fuel line and you’ll see it.

    The same web site lists the part for around $65 bucks. What I’ve been doing lately when it comes to replacing an external part of something I suspect but not sure of - is go to a junkyard and get the same part for about $10 – 15 bucks. If that’s the problem then the next time I’m at the parts store I’ll pick up a new one. It’s a lot cheaper that way.

    Here are a couple of web sites you might find helpful. They include prices, pictures, and locations of components.

  • gonogogonogo Posts: 879
    On a 99 2.2 the FPR is located on the passenger side at the rear of the intake manifold. You will see the vacuum diaphram. Remove the vacuum hose and check for fuel, if no fuel you can be sure its ok.
  • I have a 1995 GMC Sonoma, it will start but only if I hold the throttle wide open and crank it, but when it starts it is shaking real bad, and wants to stall if you dont pump it, and it smells of strong gas odor. I have had the problem before, changed the coil, cap, rotor, wires, plugs, and the fuel pump. This time around it didnt fix the problem, can anybody here give me some help. I certainly would appreciate it.

    please email me,

  • hoodlatchhoodlatch Mid-westPosts: 255

    Sounds like it’s getting too much fuel. Maybe one of your sensors or connections is faulty.

    Have you had the codes read yet? If you don’t have a reader of your own most part stores will read it for free to get your business.

    You might find the following web site helpful in explaining how the different sensors interface with the onboard computer, which is what actually runs your engine.

    In today’s engine, pumping the accelerator doesn’t do it. We like to think we’re in control but just like 2001: A Space Odyssey (1968), HAL has final word. :)
  • Ok, I read up on that site, I got to looking around my tbi and noticed a vacuum line off, once I hooked it up it didnt change anything, the truck still shakes badly, pours black smoke, and smells heavily of gasoline. My CHECK ENGINE light is not on, can they still check codes?, I cant drive the truck anywhere to get it checked, so I am stuck being a driveway mechanic. I have background in car/truck repairs, just not on newer vehicles with computers and all the other crap they put on them...

    Please advise if you can help any more.

  • hoodlatchhoodlatch Mid-westPosts: 255
    Welcome to the 21st century Jim. The era of bubble gum and baling wire are long gone. I too miss the days when all you had to do was file the points and clean the plugs and you were good to go. But – on the other hand back then 100k miles was about all you could expect on an engine life. Where as to day it’s just getting broken in.

    Sounds to me like it has something to do with the MAP sensor or EGR valve. In the past I’ve had to replace them on both Ford’s and GM’s. Sometimes they have a rubber or metallic line running to them that comes loose. Sometimes the sensor or valve just wears out.

    There’s another possibility on the EGR valve. It can get carbon trapped inside it causing it not to open and close like it should. GM is bad for that. They make an after market gasket for it that has a screen built in to help alleviate the problem. The gasket is less than $10 bucks. The MAP sensor or EGR valve are pricey.

    Be advised, in the state your engine is in now it is poring out tons of carbon monoxide. Speaking from experience, do your work outside the garage vice inside the garage. My head still hurts every time I see the dent in the wall from where I fell out from being overcome by the CO.

    Good luck. :)
  • Hey, I just wanted to extend a special thank you to you. I remember a friend talking about the egr valve in the past and when you said that might be my problem I went after it. I took it off, noticed the little plunger/piston was coated in heavy black carbon, I soaked it with carb/choke cleaner for about 30 minutes, I noticed in the end of it there was a star driver hole, so I took a driver, and gently turned it in complete circles, and pushed it up and down and completely cleaned the carbon out of it, it worked freely up and down with no hesitation. After blowing it out and getting it bolted back on and everything plugged in I had my girlfriend try to start the truck. It didnt hardly take any effort what so ever. The truck idled with no hesitation, I drove the truck around for about 25 minutes to make sure everything was fine and the battery was charging properly from the connections being unhooked, it had a small miss before it broke down, but as I stated before I changed every single part under the hood for the ignition. So, like I said, this post is to THANK YOU for your insight and guidance in figuring this truck out. I couldnt have done it without you.

    thanks again,
    Jim Brandenburg
  • hoodlatchhoodlatch Mid-westPosts: 255
    Sometimes you win, sometimes you lose. Glad we got lucky this time. Happy motoring. :shades:
  • youghyough Posts: 7
    I have bought ny truck really good looking truck but once i started to drive it i noticed that it would overheat so easily i just need some information on is there something i could add to help cool it or do i have to fix? it i need some major help on this one
  • youghyough Posts: 7
    well do you know a way i can fix this i really need to fix it come on someone has to know something
  • youghyough Posts: 7
    ok my cousin has a s10 and i know it was lowerd and we have problems with overheaing liek just driving it around gets it hot really easy and i was just wonder is there is a way i fix it so it walnt overheat as bad but im not sure what is worng with it so please help
  • youghyough Posts: 7
    ok my cousin has a s10 and it has a overheating problem i know that it was lowerd and when we run it going up the road it get overheated pretty easily and it even get so hot that it makes you hot sitting in the drivers seat im not sure what is wrong just please help me out
  • hoodlatchhoodlatch Mid-westPosts: 255
    Suggest you take it to a repair shop.
  • About 2 months ago, i was out at my familys cottage using my truck to haul [non-permissible content removed] all over, i did alot of starting and stopping. I knew that i was about a quart low, but i didnt think to much of it, so i was on my way home, and it stalled, so i pulled over, barely a drop of oil was in it. Smoke was coming out of my carb. I refilled the oil and it started up just fine. I knew that i did damage, but know i have this crazy knocking noise when i accelerate, and oil is being pushed up and out of my carb and ending up in my air filter, i dont seem to be losing that much oil, but i am also overheating, when i open my hood after 10 mins of driving, smoke will be present, not in excess amounts, but smoke.

    my question is should i try and rebuild the engine or swap it out? And will an older 4.3 fit my truck without any modifications? I have the 2.8 right now, '85 s15.
  • First, a disclaimer: I am not a car enthusiast and I know very little about cars...but I need some advice regarding my situation with my 1998 Chevy S-10 Automatic (regular cab). It has almost 130,000 miles on it. In the past 5 years, we have already had to replace the transmission system. In the past 6 months, I have had to replace the alternator AND the radiator is now busted. To boot, the AC is not working (re-charging with freon proved unsuccessful, so there is a leak) and it is getting to be unbearable (as I live in Florida). :sick:

    I just want ot hear some opinions on the matter. I am hesitant to fix the car, as it seems to be going downhill. Would it be better to put that money towards a down-payment on a new car? If I fixed these problems, how much more life do you think the car has? Any advice at all would be great...
  • gonogogonogo Posts: 879
    The way you feel I would dump it. 130K is a lot of miles, did it really need a new transmission or only a repair, chain shops don't repair, just replace.
    I have a 99 auto regular cab it has only 53K, only have done fluid and filter changes, no repairs.
  • hoodlatchhoodlatch Mid-westPosts: 255
    Due to the fact that a huge part of the repair bill is labor, and auto repair isn't your forte, I would suggest getting something new enough you could get an extended warrantee on. Extended warranties are somewhat pricey, but its nice when you can take it back and let them deal with the problems. :shades:
  • skohanskskohansk Posts: 3
    I know what you mean, been away myself. Well, back to the truck issue, I'll check this in the morning. Just hope the cat isn't welded in.
  • I purchased a used 2001 S10 in July 2005. It was a great deal, with only 10,000 miles. I replaced the water pump shortly thereafter. Now, two years later and at 30,000 miles, I'm being told that I again have an issue with the water pump and need for it to be replaced. There were no apparent issues, I simply had taken the truck in for routine maintenance. Anyone else having problems with the water pump on this truck?
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