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Chevy S10 - GMC S15 and Sonoma Engine and Underhood Problems



  • I saw on here a message about an s10 that was sputtering and making noise at idle. I'm having a similar problem and have already put a lot of money in trying to figure it out.

    Only when at speed and trying to maintain, my engine stutters. A computer check says that #2 and #3 are misfiring. I've recently had a new fuel pump installed, new plugs and wires, a new #2/#3 ignition coil and had the injectors all professionally cleaned (not just fuel additives). My regular mechanic is stumped and I can't afford to give my truck over to a dealership for several days of diagnosing right now.

    The stuttering does not occur at idle, acceleration or deceleration. It even stutters while on cruise, but not nearly as much. It seems that the instant you release pressure on the gas peddle (while maintaining speed, or during shifting) is when it seems to occur.

    Any one have some ideas?

  • hoodlatchhoodlatch Mid-westPosts: 255
    Sounds like a nice fix it-upper. About the transmission, it might be worth while to check out the vacuume modulator. Sometimes they wear out or the vacuume line gets old and leaks. Its not that difficult to change out even if it is bad. Good luck Brah. :)
  • First off, my blinkers have quit working on my 85 gmc s15 w/ the 2.8 v6. They have acted up for a while, like they would work when they wanted to, but now they dont work at all. The fuse is not blown, and the bulbs are new.

    Second, if i "pump" my gas at all while driving at slow speeds in reverse it will act like it wants to stall out, and sometimes it will. Could this be a fuel filter issue? because that brings me to my next question, how do I change that?

    My truck seems to be running very hot, coolant levels are good, oil levels are good, and my radiator is only like 2 years old. Even my hood will be to hot to touch sometimes.
  • Kirstie_HKirstie_H Posts: 10,822
    You might want to have a look at our general Maintenance & Repair board, since you've got a work in progress!

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  • dws1dws1 Posts: 1
    My isuzu d-max pick-up is too bouncy for the passenger sitting on the back seat even when im driving on a paved road. Has anybody changed leaf spring of shocks on your d-max? Can you tell me what brand and model?
  • czbillczbill Posts: 2
    I have a '92 S-10 Sonoma with 51,000 original miles. It is a 4.3 V-6, 5 speed standard transmission, extended cab. Has A/C, PB & PS and not miuch else. Every 4-6 month the truck starts running a little rough, even with the A/C off. After about a week or so of this, it won't start, cranks fine but no spark and no TBI fuel being injected. On rare occasions, such as yesterday, I can let the truck sit for a couple of hours, and after moving and fiddlng with the two module connections, the truck will start. It made it home, stalling twice but restarting. Today it won't start for anything no matter what is done to the connectors.

    Every time this happens, I install a new ignition module and everything is fine for another few months. This is a problem of the last two years or so, before it was perfect. I have replaced 4 modules in the last 18 months.

    The plugs are relatively new, the wires the same. Have run the truck at night with the hood up, don't see any sparks or lights. The ignition module connectors have been cleaned and lubricated, they are tight when installed. The proper grease is used under the module, it is tightened evenly and snugly, but not overtightened.

    Does anyone have a similar experience or see something I am missing?

  • hoodlatchhoodlatch Mid-westPosts: 255
    Your might try testing the fuel pressure with a gage to make sure your fuel pump is OK. :)
  • gonogogonogo Posts: 871
    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: 871
    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.
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