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Chevy S10 - GMC S15 and Sonoma Engine and Underhood Problems



  • gonogogonogo Member Posts: 879
    Pull the vacuum hose off the regulator, if you see fuel or smell fuel replace. Rich mixture would show up more hot.
  • electechelectech Member Posts: 2
    The LMC catalog was a good idea but did not show anything with the intake manifold. About the only parts they did not show.

    Anyway it looks like the fitting is a dorman heater hose quick connect. The only problem is that everything I look at says it is not used on this model. But I found a picture and my truck has it.

  • pre_elitepre_elite Member Posts: 7
    Just pulled my truck in my shop, hooked up Genisis scanner and found code P0172 fuel trim rich. Fuel pressure regulator? Still have misfire moving around. started on #4 at an idle then went to #2&3. Hmmmm
  • pre_elitepre_elite Member Posts: 7
    Ok pulled off FPR (fuel pressure regulator). Could not get the diaphram to open so replaced it and it did make a difference with the misfire, BUT it still has a random misfire. Just not as bad as it was with the old FPR. Going to check timing when I get to my shop at home will post info on that tomarrow. Still trying to figure this one out.
  • gonogogonogo Member Posts: 879
    The only way I know to check timing on a 2.2 is with a scanner, nothing to adjust, all electronic.
  • pre_elitepre_elite Member Posts: 7
    Ya I figured that out when I got home and started looking at it. By the way the FPR did not make a bit of difference. It was just warming up which it doesnt misfire untill it runs for a couple minutes. So going to check fuel pressure tonight and see if when I apply vacume to my regulator the pressure drops 3-10 psi. If it doesnt then must be in my return line. If it does then there has to be something electrical causing this.">
  • pre_elitepre_elite Member Posts: 7
    Ok fuel pressure is right on. About 43 KOEO and about 38 KOER. Drops like it is supposed to when vacume is applied to the regulator.
  • gonogogonogo Member Posts: 879
    I see in your first post you changed plugs, did you use factory platinum. These new electronic ignitions work best with proper resistance in the system.
  • pre_elitepre_elite Member Posts: 7
    sure did
  • junior88junior88 Member Posts: 2
    I have a 1996 sonoma with a 4.3 and it is automatic. It keeps setting a P0300 random misfire along with certain cylinder misfires as well. It is also setting a code for the crank sensor low voltage. When under load it starts dropping rpms and stuttering really bad. I have had it to several shops now and no one has been able to figure it out. When the problem occurs , I can floor the throttle and the hesitation goes away. Along with the fluctuating rpms the engine pings when under load. Any help would be greatly appreciated, I am getting tired of just replacing parts and expensive shop bills. Thanks
  • mickeymouse2mickeymouse2 Member Posts: 161
    From what you have posted;
    I would first suspect a problem with the crank sensor, or the circutry for the crank sensor. This sensor is used by the PCM to determine cylinder firing. It needs to be checked with a graphing meter like a snap on vantage. If there are any unusual vibrations, it will effect the sensor. If the repair shops you have been taking it too, cant figure it out, try one that is qualified.
  • pdempewolfpdempewolf Member Posts: 1
    1993 2.5 stick service engine soon light comes on when not accelerating for 10 sec.

    Code is 25, ATI/high air. Is there a trouble shooting check list for this problem?
  • toneygtoneyg Member Posts: 19
    this piticular problem is caused by a faulty ECM. these trucks are notorious for this problem especially the 4.3 engines in the S-10 and S15 in both the trucks,blazers and jimmy's. change this out ant it will most likely solve your problem.
  • bustedbusted Member Posts: 1
    have a 97 s-10 blazer 4.3, drove truck into 2.5-3ft. of water and stalled. Now it runs rough, sometimes doesn't want to start, without starting fluid. The truck can't get out of its own way. New plugs and wires, temp outside has hardly been above freezing. Does anyone have any suggestion of where to start? After the truck drowned we drained transmission and rear end and added new fluids. Jacked truck up to drain water from exhaust. I know cap and rotor probably need replaced. O2 sensors? CAT? Mass air flow got wet?>? any suggestions of where to begin, to keep from freezing while guessing would be great!!!

    Another problem I have that started even before the water is that on occasion(every 2 months) You will get in the truck to start it and no power anywhere, the key gets locked in the ignition in the on position. Disconnecting the battery for roughly 12hours seems to do the trick. Upon reconnecting the truck acts like nothing happened. What the hell?
  • tripp97sonomatripp97sonoma Member Posts: 2
    wondering how hard this tasks is hwo time consuming and if someone who does not mess with trucks day in day out could get it. I have never torn apart a FIE but use to work on Carb Engines. Should i get help with this tasks or tackle it myself????
  • tripp97sonomatripp97sonoma Member Posts: 2
    I have 97 4.3l my truck does the same thing with the switch I have no idea what cuases it but i did reliaze that it seems my battery cables will not tight securly and when my truck was doing the switch thing if i move the cables where the battery treminals are then it would free up the key and start.
  • dannyd303dannyd303 Member Posts: 1
    I have a 2002 Sonoma with almost 92,000 miles on it. I just had it tuned up maybe 6 months ago but since Im away at college its hardly been driven. Ever since I got it it feels very sluggish, probably because its a 4 banger but still. I have to have at least a mile or two to pass a car once I get past 50mph. 4th gear just seems to peg out around 4.5 - 5 thousand RPM. I was thinking about a cold air intake or an exhaust but I feel like im trying to make a race horse out of a donkey. Any suggestions?

    P.S. I want to know if there is a way to adjust the position of my gas pedal, its a couple inches lower than my brake and clutch, I just want them to macth up for easier down shifting.
  • boomerff373boomerff373 Member Posts: 9
    I am getting ready to swap out a leaky radiator on my 4.3 2000 S-10. I was just wondering if anyone had any tricks to make it easier to remove the quick connect fittings for the transmission and engine oil coolers.
  • flashman3000flashman3000 Member Posts: 24
    Had the same P0300 Code everyone else did a few months back, swapped, ignition, plugs, wires, coil, crank position sensor, checked fuel preasure, vacum leaks, and finally the fuel injector harness fixed the problem...for now at least.

    Question, truck still seems to hesitate during acceleration a bit but smooths out under hard acceleration. Second, now I have a really bad fuel odor coming through the cab even with windows up and when I get out. Any thoughts out there?

    I don't think I'll ever by a GM product again...at least this make and model as we put men on the moon.... and they can't give us a better product than this?


    I think I'm turning Japanese!
  • xtskillerxtskiller Member Posts: 1
    i have that same problem.if u figure it out please let me no thanks!!
  • gonogogonogo Member Posts: 879
    If you had just removed and installed the injector harness connectors a few times that would fix the problem. There is a TSB on it, pins get a film on them that needs to be removed. Thank the government for that, won't allow plating any more.
  • 2002sonoma2002sonoma Member Posts: 6

    New Member hoping you can help :)

    I have a 2002 GMC Sonoma 4x4 SLS Crew Cab. It has the V6 ("W" vin) with Automatic Trans. I have recently begun to hear an oscillating whine, or buzzing sound, that seems to be coming from the distributor. It tends to only last between 15 seconds, to maybe a minute, and then goes away. I've heard it at startup most recently, but did hear it the other day after about 10 miles of city driving. I used a mechanics stethoscope while it was running, and the sound was the loudest when i put the probe on top of the dist. cap. Any ideas ? Distributor bearing going out maybe ? (Thanks)

  • woltjerwoltjer Member Posts: 1
    i have a 1994 s10 with the 4cyl. it has a new motor and just today it is hard to start i have to crank it for a long time to get it started and have to hold the petal down to get it started it is a injected not a carb. when it does fire up it sputters real bad and puffs out alot of black smoke for a while then it idles fine until i press on the gas then it will sputter and puff more blacksmoke, then it will idle good but when i drive it every time i shift into a gear and push on the gas a little it sputters and puffs alot of black smoke im thinking fuel regulator or map sensor i need help :confuse: it pissing me off :mad: thankyou
  • goopstergoopster Member Posts: 3
    My girl friends mechanic told her she needs one of these for her 1993 4.3 s10 from what i was told it's a conection under the manifold that controls the injector pump.can't find any parts or anybody who really knows about a injector sub conector.any help on this would be nice.
  • gonogogonogo Member Posts: 879
    I all I know is the 4.3 with CPI has lots of fuel line leakage under the manifold.
  • goopstergoopster Member Posts: 3
    Thanks gonogo, nothing was said about fuel leakage just couldn't fix the wire thats part of the connector it,s going to be in my yard in a couple of days so i can tear into it and see exactly what the part looks like.
  • goopstergoopster Member Posts: 3
    problem solved :) pulled the intake manifold off and found the 2 pin connector on the injector wasen't getting any contact,the pins looked tarnished cleaned them up and good to go.Gongo i found a lot off excess fuel around this connection my guess the heat and fuel tarnished the pins.Thanks
  • zbkeeblerzbkeebler Member Posts: 4
    what should the normal operating water temp be for a 1993 4.3L non vortec. i'm reading about 220 to 235 on my aftermarket guage and my mechanic told me it might just be the sending wire i have on it the is sending a warmer temp. but i think it is just running too hot
  • zbkeeblerzbkeebler Member Posts: 4
    i have a 93 sonoma with the non vortec 4.3L(z engine code) and i put a after market water temp gauge and a new sensor in and it is reading 220-235 and i'm not sure why its so hot. i changed the fan clutch and the thermostat and the waterpump is still good. one of my friends has the vortec engine in a 94 silverado and his runs about 195 and his sending wire is metal with the spiral type cover and i just have a typical electrical wire and he thinks that is the problem and it is just reading wrong but i dont think thats it and i am not sure if the non vortec is supposed to run hotter or what???
  • mickeymouse2mickeymouse2 Member Posts: 161
    195*-205* depending on the thermostat. If your using the OEM sending unit with an after market gauge, they may not be compatible.
  • zbkeeblerzbkeebler Member Posts: 4
    i had a 205 thermostat then i put in a 180 and both of those run the same temp
  • acobboldacobbold Member Posts: 3
    I have a 2002 sls 4x4 extcab, buzzing noise out of the distrubutor, took off the cap it was full of white cake which had pushed its way down the dist. shaft and dried out the bearing, had the shaft removed and cleaned, changed the cap, need a tune up, I only have 48000 miles, check your 3, o2 sensors, each cost $166.00, they should flucuate between 150-950 mv, watch for stuck o2 sensor, usually around 520 mv to 950mv, change them all, ebay has all 3 for less than $150 complete, your dealer should be able to give you a diagram to show you their location, driver side hardest to change, must have small hands, locate passenger side and last one at the catalytic convert.
    i also had a 2x4 to 4x4 actuator problem, took it to a qualified tranny shop $500. later same problem, especially in the winter time, keep that 4.3 tuned up and buy an OBD CHECKER , (a good one) do not skimp here, it will pay for itself in the end, run a scan every month, egr valve is $303 dealer, ebay $83, all prices CND.

    good Luck
  • sanoma4x4sanoma4x4 Member Posts: 3
    I have a 2002 GMC Sanoma Crew Cab 4X4 SLS. When I am on the highway doing between 70 and 75 for about 20 minutes the check engine soon light starts to flash.
    I put on the ODB tester and it comes back 0300 for a random misfire.
    The car runs fine and has no problems at low or high speed. I have 51000 miles on a 4.3 engine. I had to replace the distributor and did a complete tune up.
    Fuel pump pressure is good. Any suggestions would be appreciated.
  • dagandwdagandw Member Posts: 1
    not hard... make sure you have gasket grease [(and) a gasket] and to disconnect the battery
  • sanoma4x4sanoma4x4 Member Posts: 3
    That almost sounds to easy of a fix, I will try it next week end.
    Thanks for the info.
  • xtremes10xtremes10 Member Posts: 1
    On a cold day or rainy day or just in the morning when you first start up it runs like a champ but after it gets hot ive noticed that nun of my power is there so say im in 3rd gear and i gas it, it skips sometimes cuts off on me makes like a skiping noise and smells like something is bruning and its only when its hot outside so im thinking something is getting hot and not running right ive done the wires plugs Mass airflow still the same problem sometimes if u try to give it gas it will stall and i have to pull over on the side of the road or w/e to let it cool off before i can go anymore and after that i still dont get to far i hope you can help me thanks
  • bajaracerbajaracer Member Posts: 1
    I have a 2001 Sonoma with the 2.2 4 cylinder engine. At low RPM (under 2500)
    I have an engine vibration to the point of shaking the dash board. At speed
    with the truck it all smooths out. The truck has 115k miles on it. My first thought
    is that the timing chain and tensioner is worn out and changing the timing
    at low RPMs.......any other ideas? Thanks
  • cinqoman22cinqoman22 Member Posts: 1
    I have a '94 sonoma that does not have the original engine in it. Unfortunately, I got the truck after the engine switch. I don't know exactly what type the engine is, and I can't seem to see the code stamped on the rear of the block. The engine has 2 injectors that spray fuel downward into what looks like a carb, but I don't think it is a carb. Any help would be appreciated.
  • mickeymouse2mickeymouse2 Member Posts: 161
    GM used a 2.2L =4 cyclinder and a 4.3L =V6 on that. The Fuel Injection is called Throttle Body Injection TBI for short. Even though there has been an engine change, it is one that will bolt up to your transmission. You either have a 2.2 or a 4.3.
  • the_big_althe_big_al Member Posts: 1,079
    I would say going through the wheel well as hoodlatch suggested is the best way. Going through the well also works well for the spark plug behind the steering linkage. I changed all my plugs by going through the wheel wells rather than trying to lean down through the engine bay.
  • the_big_althe_big_al Member Posts: 1,079
    *Also Posted in Maintenance and Care*

    I had hoped that I would never have to pose this question, but here goes. I have developed an oil leak on my '01 S-10 4.3 2wd. 105K miles. Maintenance has been good - oil changes every 3K or so. Never more than 4K, and a lot of times less than 3K. But just recently I noticed oil underneath the truck. At first I thought it was a loose plug, but had it replaced at the last oil change. Filter is also tight. I pressure wshed the bottom of the engine to better able to tell where it is coming from and it appears to be coming from the rear of the motor between the motor and transmission.

    That seems to me to be the rear main seal? I don't seem to leak very much - about 1/3 of a quart in the last 1000 miles. So it's not a major problem, but I hate having oil drip becuase now I have to watch where I park for fear of leaving a nasy spot on someone's drive.

    I also switched to Mobile One on the last oil change, but I doubt that has anything to do with it. The reason I had the oil changed is I noticed oil collected on the bottom of the pan and since I was almost due anyway, took it in and made sure the plug was replaced. When I had first inspected it, that's where most of the oil was collected and so I surmised that's where my problem lay. But since changing the oil and cleaning the bottom of the engine, I still seem to be dripping.

    So now I am in quest of locating and hopefully repairing the leak with out too much hassel or expense.
  • boomerff373boomerff373 Member Posts: 9
    I was wondering if anyone had a good way of testing the fan clutch on my truck. I don't think its locking up all the way. Any help would be appreciated.
  • gonogogonogo Member Posts: 879
    Well if it is running hot and you don't hear the roar, can't miss it, it's not working. When cold give it a spin by hand with engine off, it should not move much, should have resistance.
  • boomerff373boomerff373 Member Posts: 9
    The water temp runs around 200,doesn't seem to really go down that much. Fan doesn't seem to be engaging and roaring like you said. Also moved the fan when the motor was cold, not much resistance there. Gonna have to replace it. Thanks for you help
  • jeff_neufeldjeff_neufeld Member Posts: 1
    Hello i have a 1998 Gmc sonoma, 4wd 4.3 liter, the clicking is kinda coming from under the front of the truck..I was reading about it and a forum said that it could be the oil.In th transfer case. Does anyone know if thats the case? and if so where is the transfer case( i think i know just making sure) and how easy is it to change? it only does it when i accelerate hard...And i dont hear it at high speeds thanks my email is neufeld_jeffrey@yahoo.com

    thanks alot
  • foxxracer2777foxxracer2777 Member Posts: 1
    my s10 runs smooth after doing plugs wires cap and rotor but once i get higher into rpms it backfires. kindof sounds like a pop. all the wires are good and in correct order. timming is ok. any ideas. please email me them because all this writting on one page hurts my eyes. foxracer2777@Yahoo.com
  • boomerff373boomerff373 Member Posts: 9
    Getting ready to do a tune up on my 2000 4.3 S-10. Does anybody have any tips that will make it easier to get to the spark plugs. Doesn't seem like its easy to get to them from the top.
  • flytesweepflytesweep Member Posts: 2
    I have a 94 s-10 4.3 vortec 6cyl. engine. The exhaust is very very noxious. When i start the engine it actually isn't too bad. As it warms up the exhaust gets very rich as if there is alot of unburnt fuel. White smoke comes out of the exhaust .
    The truck has been sitting awhile and the gas smelt like varnish at first. The tank sensor is not working but i have gone through the bad gas and have burnt about 2 gallons of fresh fuel.

    How can i resolve this problem.
  • sonoma4x4sonoma4x4 Member Posts: 1
    I have a 2002 GMC Sonoma 4X4 crew cab and get the same code (0300) when I drive at 60 on the highway. I have no hesitation at any speed and the truck runs great. Do you think the crank sensor could be the problem? I have replaced the plugs, wires, rotor. cap, distributor, fuel filter, pvc.
  • paulbakerpaulbaker Member Posts: 1
    Assuming it is tuned up I would pull the EGR valve and clean the carbon deposits or simply replace also check the rubber hose connections for cracks Especialy the ones going to the egr vaccuum.
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