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Chevy S10/GMC S15-Sonoma: Problems & Solutions



  • steve.
    i'm going to guess computer, because i'm having the exact same problem. i just put in a brand new complete crate motor from gm and still have the problem.#2 cylinder is fuel fouling. my new motor came with injectors, sensors, throttle body, coils, plugs, wires. only thing left is computer.
    good luck.
    maybe someone will post that help us both.
  • My god! that's exactly how it happens, i think that will be!!!. I didn't think that was the problem because the mechanic said it wasn't but now that you describe the problem, i'm sure that you are right. Thanks
  • I have a 99 s-10 with a 2.2 in it. For the mileage it could not run any better, however when I try to start it when it is still hot, usually after it sits for about an 1/2 hour to a hour it doesn't start well at all. Usually takes about 10 to 20 cranks to get it to finally run. Once it starts it runs just fine, doesn't miss or anything. When I start it in the morning or in the dead of winter when it's cold outside it starts on the first turn. I've changed just about everything including plugs, wires, ign. module, coil packs, alternator, starter, TPS and probably a few other things I can't think of right now. Also, shouldn't my hwy mileage be about 30 or so? I'm only getting about 22mpg on the interstate. Should this be some kind of hint??? Any help would be much appreciated. Thanks.
  • alcanalcan Posts: 2,550
    Remove the vacuum hose from the fuel pressure regulator and check for the presence of gas. If so, the regulator diaphragm is ruptured and requires regulator replacement.
  • Just wondering - Is your engine running a little too hot ??? Could be that it's running on the hot side - then you shut it down - and all the latent heat in the system continues to elevate the engine temp a little more (after a 1/2 hour or so ...) - but after that time - the engine cools down and it starts OK... Check the temp, Gauge, Thermostat, etc ... Just a guess - but easy to check ....

    Good Luck!!
  • I actually went to a lower degree thermostat. That made no difference. My truck doesn't run hot at all, well except when I have the air conditioning on. Thanks for the regulator tip, I will for sure check that out.
  • Hello there, just looking for a bit of help here. I ran into this problem and cant seem to solve it. I have a 97 chevy s-10 V6 4.3liter, 4x4, auto. Now I have started to have some problems with the electrical gauges, 1st, when I turn the lights on the air bag signal comes on, turn the lights off, light goes off??? 2...check engine comes on after I have been on the highway and reach 100km/h for more than 10 mins... but eventually turns off after I have driven in the city for a day or 2 at relatively slow speeds?????? I have brought it into a few different garages and had them run the computer checks, but they cant seem to find a problem.... The last problem has to do with the voltage meter,, it is constantly jumping up and down from 10 to 14 on the volt meter.. I have changed the alternator, that was not the problem, I have repalced the positive battery cable and the power wire leading to the back of the alternator??? So this has become a process of elimination that is becoming expensive.... any one might know what the problems may be????? Oh last thing My truck has been through 2 alternators in the past 8 months, now I know thats not right,,, so whatever is causing my alternators to fry out I assume is what is causing my voltage meter to jump up and down??? any help or input would be appreciated Cause I am stuck!!!
  • Hi,

    Sounds like you could have a short, probably in one of the power cables
    running to the dash. You can try pulling the possitive cable off the battery and
    see if the truck dies. Also, does the alternator your putting in have voltage
    regulator built in, or is your regulator mounted somewhere else, if seperate
    that could also be the problem. good luck!
  • hey tjdude,

    I replied to your tps problem, just wanted to let you know about the other
    code they pulled on your truck, that code also has something to do with the
    tps, mine also pulled another code from the rearend, and mechanic said it was
    something to do withover acceleration on the rearend, like I had did a burn-out
    or something. So, what it is, is the tps being bad is telling the computer that
    the truck is over reving, so inturn the computer retards it so you dont blow it up.

    take care
  • Having transmission problem, when code has been reset shifts fine, when it gets hot trans starts slipping again code pops back. Dealer saying its a solenoid problem, trans shop saying its an electrical problem, or maybe a thermostat issue. Does anyone have any ideas??? Need help :cry:
  • alcanalcan Posts: 2,550
    P0758 = Shift Solenoid B Electrical/ 2-3 Shift Solenoid Circuit Electrical

    Solenoids are electrically operated valves, so they're both right. Pretty simple to use the diagnosis flowchart for P0758. Might want to start by checking the trans wiring harness connector.
  • 1999 S10 V6 AOD just yesterday after 150,000 miles my truck started shifting funny into second gear. RPMs way up before slipping into second. Up till yesterday everything was working fine. Reverse is now gone also.

    Any suggestions
    Jay Baker
  • alcanalcan Posts: 2,550
    Are you sure the shift is into 2nd and not 3rd? If the sun gear drive shell fails (common problem) it'll lose 2nd, 4th and reverse. Requires removal and disassembly, and at 150K you might as well have it rebuilt.
  • I have a 95 2.2 S-10. I have just put new wires on that are 8mm and I still have the spark jumping through them(OE is 7mm). I have checked the plugs, all the grounds, and I have also ohmed the coils and they are ok also. So what else could be the problem???
  • alcanalcan Posts: 2,550
    Use AC Delco wires.
  • The thing is I have used AC DELCO, and they do the same. That's why I now have ACCEL performance wires witch are 8 mm.
  • Only slips into second then its fine. Just changed the fluid and filter tonight. It looks very clean but I change it more often than needed. Still no reverse and I have not taken it for a ride to check on the slipping. With two kids in college I doubt I will be having the trans rebuilt. I can get one with 29,000 from a yard for $500.00.
    Any idea what a rebuild costs?

  • alcanalcan Posts: 2,550
    Usually around $2,000 in my area. Make sure the salvage yard unit has a warranty which includes labor if it's a dud and has to be replaced again.
  • 1989 GMC S-15, 4.3l engine. When it's cold it will not hold an idle. I have found out today that if I gun it and the tranny jumps into the next gear it will be OK. Is there a sensor or something between the engine and tranny that might make this happen? My mechanic had it for 7 weeks and called uncle. So far the fuel pump, filter, relay, pressure reg., strainer, computer and prom, coolant temp sensor, ignition module, both TBI injectors, map sensor and Idle air control motor have been replaced. Also the the sensor ground has been repaired and the TBI base gasket replaced. Does anybody out there have a clue? I live in Alaska and winter is almost here I need the truck to idle.
  • Try the EGR valve for carbon,or the PCV valve, I have also have had the MAP sensor do the same thing. I would try the MAP sensor first. I hope this will help.
  • Joe, I have a real problem with a 98 S-10 and it may be related to the "dead fuel pump" dilemma. Replaced fuel pump assembly and filter. But to no avail. Still had a dead fuel pump when ignition key applied. Jumpered across FPRelay and engine would start and run----as long as I had the relay jumpered. When I removed the jumper, the engine immediately shut down. Looking at the schematic, the oil pressure switch should have kept the pump running once the engine started. I get battery voltage at the PCM with ignition on, but the fuel pump relay will not close. Haynes book is not very clear on the ignition circuit layout. Really need help here.
    Joeygeno :confuse:
  • FYI-----sorry I am late with this, but when you removed the bed-----you also removed the ground. Fuel Pump is grounded at the left rear, along with the lighting harness. (Two Grounds) and grounded to the frame. You would have had to remove them to take the bed off.
  • Alcan, please help!!!
    I am not getting voltage to the FP relay when the ignition switch is turned on. If I jumper the switch contacts of the FPR, the truck starts and will run-----But if I remove the jumper, the truck immediately shuts off. Schematic shows the oil pressure switch should have kept the FP running. Cannot figure this one out. Your answer to Jameyw in March 14 was very helpful in at least understanding the system function. I do not have a decent schematic of the PCM other than Haynes,. Please help
  • We have a 99 Chevy S10 and I need to know where the Manifold Absolute Pressure Sensor is. We have been having problems with it cutting out and dying on us, sputtering. When it is cold it is fine, but once it is hot forget it. We have done so many things to it by now. We have checked a few sensors, but would like to check the voltage on the manifold absolute pressure sensor. Thank you.
  • joe3891joe3891 Posts: 759
    Sorry been busy installing DSL, the 99 schematic does not have the fuel pump relay. The relay coil is power 12 V from PCM, DK GRN/WHT # 2 relay wire C2 pin 8 at PCM black 80 way connector. #1 relay coil is BLK/WHT ground.
  • Thank you so much for replying. My 98 has a purple, (16pin), blue (24pin) and brown (24pin) . But as I said, I only have the haynes schematic and it does not have PCM pinouts or show the source IGN power . But I am sure the fuel pump does not run when the ignition sw is on. If I jumper the fuel pump switch contacts at the fuel pump relay socket (fuse box), the pump runs and the truck will start. With engine running, removing the jumper will immediately shut the engine down.
    According to my haynes schematic, once the engine starts, the fuel pump oil pressure switch should takeover.. My assumption is that the fuel pump relay (Fuse box) is only active in ignition start, and the oil pressure switch takes over when the engine starts.??? Again, I am confused
  • alcanalcan Posts: 2,550
    The schematic is below. Do you have V+ at the relay's green/white terminal with the engine running?
  • My friend, About a week ago i got some major smoke bellowing out the exhaust pipe on my 95 sonoma. I found out it was my Head Gasket. Im an auto part driver for a major parts company, so i asked quite a few mechanics what they would charge me i was quotes frome 600 ta 800. ok and a sister company of ours right up the road can mill the head and pressure check it at there place for 45 mill & 25 pressure check. Long story short since i have a good friend thats a mechanic i decided to do it myself.....(NOT RECOMENDED)....Luckily i get a discount on parts so i got a few gaskets, a few hoses, some head bolt$, much brake and carb cleaner, & a few other last minuite back to the store things. Got my head milled and P.C. for 25 bucks<---DEAL Paid like 50 bucks for all the gaskets,etc... all in all from the lowest quote i saved like 400 dollars.There 2100 sounds a little high.I am a real novice and my friend pointed most of it out to me and i should think a shop worth there sand can do what i did in no time flat.ALL I CAN SAY IS SHOP AROUND. To as many shops it the area you can call. sorry for the ramble..
  • Thank You,
    I will check voltage and get back to you. Do you have a component location schematic for the PCM system on a 1998?
This discussion has been closed.