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1992 Chevy S-10 FUEL PROBLEMS?

Tiny
PLUMBER922
  • MEMBER
  • 1992 CHEVROLET S-10
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 20,000 MILES
My s10 blazer has a V6with CPI, recently the engine started acting up almost like it wasn't getting enough fuel. So I started with the fuel filter, it still ran the same next came the new fuel pump, same results. My attention shifted to spark, I replaced the coil, plugs, plug wires cap & rotor and had the ignition module tested. After all this it ran exactly the same, so I switched gears again and replaced the TPS and the oil pressure sensor.I am running out of things to replace and money to replace them, after listening to the engine more closely it almost sounds like its getting too much fuel because if you are driving it you can get it to clear out and run properly until you let off on the gas. My next move was to replace the fuel pressure regulator but I'm going to wait for some more advice. Replaced fuel pressure regulator this afternoon and the problem is still there and maybe has gotten a little worse. Engine will idle fine and problem begins when you step on the gas, but can relieve itself if you gently let off the gas.I don't have a clue!Any help would be greatly appreciated.
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Wednesday, March 25th, 2009 AT 11:49 AM

14 Replies

Tiny
RACEFAN966
  • MECHANIC
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Ok first off have you checked the fuel pressure? If not I would and then go from there. Now the other common thing with this fuel system is under the upper plumen the fuel lines like to crack and they will leak not a lot but they do. It will usually cause starting problems idle problems and so on. SO what you do if the pressure seems ok is remove the upper plenumn and look for clean area around the fuel lines where they connect at if it is very clean or wet then there is a repair kit to fix that. Let me know what you find and we can go from there.
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Thursday, March 26th, 2009 AT 10:03 AM
Tiny
PLUMBER922
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Checked fuel lines when I replaced the fuel pressure regulator. The area in there was dirty and had a oily residual on it, but no signs of fuel. Pressure is fine.
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Thursday, March 26th, 2009 AT 10:56 AM
Tiny
RACEFAN966
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Have you cleaned the mass air flow unit? If not get some mass air flow cleaner (NOT CARB CLEAN) and remove it and clean it and get back to me with how that does. If it seems to do better then we will test the mass air flow unit but you will need a digital mutli meter. Let me know how it goes.
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Thursday, March 26th, 2009 AT 11:05 AM
Tiny
PLUMBER922
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Cleaned air flow sensor, did not change anything not even a little. Did notice that if you press down hard on the accelerator car does back fire like its getting too much fuel. At this time problem has become so bad vehicle can no longer be driven.
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Thursday, March 26th, 2009 AT 12:18 PM
Tiny
RACEFAN966
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OK this is good as it will give us a place to start. Now is the check engine light on? If it is then call around to the local parts stores and find one that will do a free scan and scan it and write the codes down and then clear the codes. I also need to know if you have a digital multi meter so we can test the mass air flow meter? I would also like you to unplug the mass air flow unit (electical plug) and start it and see if it will idle good even if it only for a few minutes. Is the backfire going into the intake or the out the exhaust? Get back to me and we will go from there.
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Friday, March 27th, 2009 AT 10:20 AM
Tiny
PLUMBER922
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I bought a code reader when this first started and I have yet to read anything but a 12. The backfire is going into the intake.I do have a multimeter. Just unplugged air sensor, vehicle idled at 1000 rpm instead of the usual 800, but stayed running. Bendix in starter just gave up the ghost so I'm off to find a starter! If I don't figure this out soon the only thing I'll need is a lighter!
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Friday, March 27th, 2009 AT 11:29 AM
Tiny
RACEFAN966
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OK when the starter is back in get back to me and we will test that Mass Air Flow unit as with the test you did tell us it may be bad.
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Sunday, March 29th, 2009 AT 9:32 AM
Tiny
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Replaced starter today, ready to start things up again. Did find out that the part I cleaned and tested was the intake air temp sensor and was told that this model of engine ( engine vin w ) does not have a mass air flow unit. Could this possibly be a timing chain issue?This started happening when my daughter was forced to slam on the brakes to avoid an accident and after that the car started acting up and I had to trailer it home and has not run right since.
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Tuesday, March 31st, 2009 AT 6:04 PM
Tiny
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Sorry your right you have throttle body injection not multi port. Ok have you sprayed carb clean down the throttle body to see if it would start? If not try and let me know what it does. If it does start then a fuel pressure test is needed.
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Wednesday, April 1st, 2009 AT 9:47 AM
Tiny
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Actually I have a CPI not a TBI. I rechecked the fuel pressure and found something interesting. When you turn on the key the pressure is 54lbs after starting and at idle it remains around 54 lbs but as you accelerate and the engine starts to bog down the pressure increases to around 62 lbs and levels off at around 54 as you let off on the accelerator and the engines stops bogging. Any ideas now, I hope so because the next thing I was going to try to replace is the timing gears and chain and I really am a plumber and not a mechanic.
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Friday, April 10th, 2009 AT 6:33 PM
Tiny
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Yea the fuel pressure is to low. It need to be 60-66 psi as I have already said. So either the fuel pump is bad or the pressure regulator is bad.
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Friday, April 10th, 2009 AT 8:53 PM
Tiny
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Both have been replaced along with the fuel filter. Is it possible I could have gotten a bad part, I bought them both at oreillys.
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Friday, April 10th, 2009 AT 9:04 PM
Tiny
RACEFAN966
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Yes you could have gotten a bad fuel pump. Have looked at the plastic lines that connect to the back of the main injection unit under the plenum? These lines like to crack and leak and this can cause the fuel pressure to be low too. They make a repair kit for this if this is the problem. What you will have to do is remove the upper plenum again and see if the lines are wet or look like they have been washed clean like fuel is leaking. Let me know what you find.
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Friday, April 10th, 2009 AT 9:27 PM
Tiny
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Just to let everyone know it turned out to be the CPI unit itself, even though it never leaked or showed any signs of not working, I went ahead and replaced it because I ran out of things to replace. Car runs like new. Thanx for the suggestions. Greg
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Thursday, April 23rd, 2009 AT 3:20 PM

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