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Chevy S10 - GMC S15 and Sonoma Starting problems



  • I had a similar problem that turned out to be a flat spot on the fuel pump (inside fuel tank)
    good luck
  • blee1250blee1250 Posts: 2
    my truck has a lil problem it starts fine and then if i drive it for over ten mins say stop ans wawa and when i come out n try to start it it will just crank untill i hold the gas all the was down then it will start but studder and then after a min of holding the gas it will calm down n run good...but if i drive it and park it then wait like a hour or more it will start no problem???i dont get it
  • brunorexbrunorex Posts: 7
    My S-10 (97) had the exact same symptom. It was the fuel pump. Garage will have a tester that will actually show the problem on a electrical wave. Hope that helps. New fuel pump was installed two years ago and it fires first time every time no matter how long it has been druven.
  • Hey blee, i was wondering what motor your sonoma has (engine code will help)? I've had similar experiences with my 93 s-10 2.8 V6 TBI but there is a good chance we have different motors. I would test the fuel pressure, also when it doesn't start up try starting in clear flood mode (hold gas petal at more than 90% wide open when you crank it) if its flooded it should start right up. If this is the case you could have leaky injectors (assuming you have a tbi) fuel pressure regulator, fuel pump, fuel filter, so on and so forth. There are quite a few things than can attribute to this problem. Maybe start with some basics like cleaning your EGR valve and o2 sensor. Or just start replacing sensors all together. It took me a while to get my truck running perfect and a little more information would give me a better idea of what you should be looking to clean or replace.

    Hope i can help

  • blee1250blee1250 Posts: 2
    yeah i have the 2.5 4cyl and if i drive it then when i go to start it again and if i press the gas pedal to the floor then yeah it will studder for a min then run smooth...and thats only hot start cold start it is no problem as if i waited a hour to try n start it again
  • caleb33caleb33 Posts: 2
    Ok im having problems with a 98 s10 2.2 cyl. when the truck cranks it acts like its out of time or something it just started happening one day. The truck will still run just a really hard time to start. I have had several codes pop up them being p0335 p0342 and i believe the other was p1626. I replaced the cam sensor and crank sensor. Codes still seem to be popping up and I dont have a clue where to go from here. I inspected all wiring as good as I could without a ton of teardown. Once running the truck runs fine. Sometimes it starts better than others but instead of a constant cranking like you would hear on a car with the coil unplugged it wants to jump around and not be consistent.

    Any suggestion
  • brunorexbrunorex Posts: 7
    I purchased a high mileage '97 S-10 4 cyl three years ago that was doing the same thing yours is. Once it was started it ran fine. It was the in tank fuel pump. My mechanic showed me a diagnostic printout on the current at the pump before and after changing the part. Showed what I can only guess must be a flat spot develops on that electric motor. Has started perfectly cold and hot ever since. Hope that helps.
  • caleb33caleb33 Posts: 2
    k The think that has got me tho most confused is the codes. To my knowledge those codes have nothing to do with the fuel pressure or anything. Do you believe there might be a wire grounded somewhere? Or am i totally wrong about them not relating?
    Thanks for the help
  • brunorexbrunorex Posts: 7
    Sorry I am not more knowledgeable but I do know that sometimes a code is generated because that is all the computer knows when certain symptoms happen. There is a place where you can hook a scope to view the current being drawn by the fuel pump but unfortunately I don't have that info. Maybe a new post requesting instructions for doing that particular diag might find you some kind soul who has experience with it. Good luck.
  • pingwoopingwoo Posts: 1
    Radiator split, truck over heated and bad things happened. Removed head took to shop and they did what they do and I put the head w/ all new gaskets etc. etc. back on engine. Now when we go to start the truck all I get is "click, click, click" from the starter. :mad: Took starter and battery to shop for testing both test good. :confuse: What else could I be missing? Engine is not seized I assume because can turn at crank w/wrench. HELP PLEASE!!!!!
  • brunorexbrunorex Posts: 7
    Had a similar problem with my 95 S-10 after badly overheating. Found one of the stater wires had crispified during the overheat. If the wire was jiggled when key turned to start it would start. No jiggle no start - replaced wire and warranty replaced starter (for second time) and has now started perfectly for 6 mos. Some reason the wire only making partial contact when jiggled was damaging the new starters. Good luck.
  • rfletcherrfletcher Posts: 24
    187000 mi., well maintained. Vacuum steady at 22. Reported, by shop, fuel pressure normal.

    Starts and runs well when cold. After 20 / 30 miles will restart easily, but only, if throttle held down. Has a long history of, intermittently, dieing at any speed when hot. Will usually restart and run for 100 yards, 100 miles or six months. No pattern. Recent problem is a new twist. Has not died while driving, recently. Hot start problem is new and consistent.

    Preparation for a trip in May, had a " professional"---? tune up. Plugs, wires, fuel filter and injectors cleaned. All else tested and declared OK. [$300.00 plus]. Four times on trip it died at 70mph. Restarted each time with throttle down.

    Since trip I have replaced the O2 sensor, coolant sensor and TPS. Replaced the IAC. Replaced all sensor connectors [solder and shrink tube]. Added ground wires back to the neg. battery. Replaced EGR solenoid. Problem is somewhat different but not solved. For what it's worth: I can not get voltages, at the TPS, down to suggested values. The TPS is not adjustable. They are high but very close. I could adjust the mechanical stop but that would close the throttle even more. It seems to want open throttle.

    I am off tomorrow on another long trip. See what happens. Any thoughts appreciated.
  • rock88rock88 Posts: 3
    OK, had this for 7 or 8 years. /Gets a quirk and will not start sometimes. warm cold, winter, summer make little difference. prior owner installed fuel pump, used? I can hear the pump start and prime. It sometimes starts, but lately will not start without a little fuel, or starting fluid. Today, was had a little rain, and a damp morning... NO START AT ALL... I let it sit with the hood open, 2 or 3 hours and then tried to start, and it popped. Added a little start fluid, started right up! 8 hours later, hard to start, but did.. again, with a little fluid! Been through 2 starters so far, I have tried alternate brands of battery, and for a while. the sears die hard, seemed to improve this issue for a few months... Now, it is not... Also, 4th alternator, LIFETIME WARRANTY, and it is producing 14.4 volts. Just checked it last week. Also, installed a new cap and rotor last fall... Now, with winter coming on, I need to have this run, as I am on call... Engine is a 4.3, 170K. I have run e 85, at 40% from time to time... Fuel filter is impossible to change. Seized... Even mechanic at shop could not get it changed. I thought about a torch... Maybe solve the entire issue! HA HA!

    SO, time, moisture, seem to be the main enemy. Time is the primary... Moisture seems to be solved with the starting fluid, MOST of the time. If I run it, every day, the probelm is usually less. But as of late, even 10 hours can cause the issue.

    This truck has all the power I need. runs FLAWLESS after it starts! It is sometimes is a little slow and low on power for first few seconds of running.. Once it starts, it almost NEVER dies. it will run interstate speeds towing a full size enclosed trailer.. I get 18 to 21 MPG average.

    SO, any suggestions? $$$$$ is a factor, as I was unemployed for a long time and just getting back to a normal life... A different SUV is NOT an option.

    Besides, I am courious and I can not sell it like this and have a conscience...

    If I fix it, I will run for 1 more year, but i can not sell it to anybody that can not deal with the quirks...
  • rock88rock88 Posts: 3
    Just a thought, check for a bad vacuum line... Especially the one that corsses over the back of the engine.. I have a 96, and I think the 91 is the same... Can be a bad rubber union in the valve cover... Look for the little things... I work on small engines... Use carb cleaner to check for leaks... Spray the cleaner on the point is question and note any WELL VENTILATED AREA, OUTSIDE and AWAY FROm FLAME.. A little spray will do... It could also be electrical... Start engine, spray a mist of water and watch for arcing... Use a simple spray bottle and do at night... Makes it easier to see any sparks...
  • Thanks for the tips. I did check the vacuum lines even though the vacuum is solid at 22 and up with acceleration. That part is just a pain in the neck but on the trip my old problem came back. Engine suddenly dies at any speed. Restarts easily. Seems to be worse when hot. Actually it only happens when it's hot. Yesterday I replaced the EGR valve. The old one was not very dirty but considering the miles I replaced it anyway. Did not help but during testing found the recently replaced Vacuum solenoid was not working. It's not getting the ground circuit from the ECM. While inspecting wires back to ECM found two of the three wires shorted deep in harness. Replacing the defective wires did not solve the problem so now suspect the ECM is fried due to the shorts. Now I am really in over my head. How do you test the ECM? Do not think so but could there still be condition elsewhere that prevents the ECM from turning on the solenoid? I do not know when the EGR valve is supposed to operate but running the engine up to normal temp. and accelerating to 2500 RPM never opened it. Well---tomorrow is another day and probably another ECM. Strange, that super tech, master mechanic that charged me $300 for a tune up, missed this little detail.
  • where is the fuel filter on my motor.its a 4.3 liter.changed plugs and wires and three vac hoses now wont start.HELP.
  • tomygtomyg Posts: 13
    I have the same engine on my 92 sonoma.The fuel pump is in the gas tank.The fuel filter is bolted to the frame just in front of the gas tank.I hope that helps.
  • I have a 98 chevy s10 with 237,000 on it. In the mornings when its cool out it starts right up. When is warm out it cranks for 4 to 5 sec and then start but starts rough. If I shut it off and start it back up right away it starts fine. If I wait 15 minutes or so it starts rough. Once it starts it runs fine.

    So far I have replaced the fuel pump and the fuel regulator. Tested IAC, TPI and Air intake temp sensor.
  • sonomamalicesonomamalice Posts: 1
    edited November 2011
    2000 GMC Sonoma SLS 4.3 2x4 Automatic. Slightly under 80k miles. I've owned it for the last 47k miles. Never did anything to transmisson. Fluid is clean. Not sure if it ages like brake fluid.

    Here's the conundrum, Sometimes the truck starts perfect. sometimes it makes a grinding noise like it just can't connect with the flywheel fully. First starter (cheap remanu. from AAP) the housing dome basically exploded. Second starter (Brand new from quality built) on the third start sheered the dome clean off. Third starter (NAPA remanu) Im not sure is bad. One of the two wires to this starter had broken so I replaced it and installed a new starter (Remy from AAP, brand new). First start with the Remy was the strongest I've heard in the past 8 months. Second start on it made that grinding noise. Third start was in between both. Since it sometimes has a good start , and sometimes sounds like it's grinding and going to explode, could I have a bad flywheel? Either missing teeth or a 'flat' spot? This was the main explanation I got from all the mechanics I've talked too.

    Doesn't matter if it's cold hot wet or dry. The problem is completely random.

    History: New plugs about 38k miles ago. new drive shaft 6 months ago, the u bolts at the rear broke. This happened when I was driving abut 70mph and made the truck bounce violently. Not sure if this could of cause other internal damage that took a bit to turn into a problem.
    Don't know what other information you need. Also, does my flywheel have 153 or 168 teeth and when I look for a part it asks if I want internal or external engine balance. Guessing internal? Also if I replace it, suggestions on a replacement? Money doesn't matter, I'd rather pay for a good part and save the worry then save some dosh and have a repeat down the road.

    Thank you ahead of time and sorry this is such a huge post.
  • zaleszales Posts: 1
    My 96 s10 won't start. a little gas in the throttle body, and it starts and runs fine. will start again after that but not after sitting a while. baffled
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