Mechanics

TRUCK 4.3L TBI. ENGINE SHUTS DOWN LIKE IT IS RUNNING OUT OF FUEL. FUEL PRESSURE IS GOOD. IGNITIONS IS GOOD AND HAS GOOD SPARK. THE INJECTORS JUST STOP WORKING. I CAN POUR A LITTLE FUEL IN TBI AND IT RUNS. I CAN WAIT 5 TO 15 MIN AND TRU

1992 GMC Sonoma • 150,000 miles

Fuel pump stopped working. I replaced complete fuel pump/sender assembly. It worked great for about one month. The fuel pump is making normal noise as if it is working. It does have correct fuel pressure. Engine has spark. When running engine runs very good and has good power and does not stutter like it was doing before fuel pump was replaced. I am thinking fuel pressure regulator which is part of the throttle body but can not be tested. Or ECU is doing something to shut injectors off. Is there some other test or recomend what to check? The problem is it is not consistant. It can start up and run great, and restart. Then the next time it would not restart. I do not like to just buy parts without confirming it is bad.
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Aj3harty
February 5, 2012.




I'M NOT NO AUTHORITY ON YOUR RIG

IMMA JEEP CJ GUY

I SAW YOU HAD BEEN WAITING

OTHER THAN THE REGULATOR---COULD IT MAYBE BE A RELAY ALONG THE WAY, INTERMITTENTLY SCREWING UP. MAYBE YOU HAVE IT'S "TWIN" FOR ANOTHER SYSTEM, AND SWAPPING THEM MIGHT DETERMINE IF IT IS INDEED, DEFECTIVE.

JUST A THOUGHT, OTHERS STILL MAY JUMP IN W/ A BETTER ANSWER THAN MINE

THE MEDIC

Tiny
CJ MEDEVAC
Feb 5, 2012.
Check and test the distributor pick-up coil resistances

Rasmataz
Feb 5, 2012.
Tested Dist pickup coil is good at 850.

Tiny
Aj3harty
Feb 20, 2012.
Here is some more info that may or may not make a diff. When I start it and keep it rev'd up. It will keep running and will not shut down.(It never died on the freeway) I can do this as long as I do not let it idle. Yesterday when I went out to start it. It started and ran 6 times, rev'd up and at idle. I was hoping after testing pickup coil, I might have fixed some kind of connection. Just when I was about to tell my son it was fixed. It died, Tried to restart again, No injector pulse to injector from ecm. I am thinking that when I put fuel in tbi and it starts, the rpm's are up and it is then getting a signal from something for the ecm to send pulse. This is were I think from my research, that the signal comes from the pickup coil. But it tested good at 850. When the engine is running I can pull/tug/wiggle wires at ecm/distributor/all sensors. Engine keeps on running nice n smooth. I am about to give up.

Tiny
Aj3harty
Feb 20, 2012.
Had similar problem with my Dad's '86 T-Bird, on his it was inability to idle (sometimes it would, sometimes not). It was the injectors, they are not "Monitored" by the Computer, The computer just "operates" them. However when they act up, they do make other things throw codes randomly.

The 1st thing we did was the coding w/ the Scanner--It take s a bit to catch onto--listening/ watching the flashing light/ beeps and counting---watching it go thru a sequence

I was pulling my hair out and made several trips to the salvage yard and obtained nearly every sensor (2-3 of each) off of T-Birds and Cougars

I thought surely they all cannot be bad, I got a bagful for like $10!

My intentions were to figure out which one was being evil----THEN BUY A NEW ONE!

My Dad and I wound up taking it to the feller that the stealerships take their problem cars to. He let me watch the process.

Everything was in perfect order, He put stuff on an oscilloscope, and explained what he was doing. The only thing he came up with that was not perfect was the TPS--I had replaced it with 2 from the salvage yard and wound up buying a new one from Advance Auto (This new one was supposedly bad)

This feller even confirmed "Base Idle" was dead on (another learning experience). Don't mess with the adjustment screws--I learned that throws the computer out of sync with the sensors---there is a specific procedure to get it right----at least I had got it right before this guy checked it out

Dad paid the feller $200 and off to the stealership for the "OEM TPS". It's cost was much more than Advance Auto

Guess What?

This did not work, in fact, I took it back and got another

Same deal. Will not idle!

I was on the Verge of Suicide.

My buddy had went back and got the whole throttle body off of a wreck that had low miles, for $20.

I laughed when he showed up and gave it to me.

He said this is the only thing we haven't tried, the price was right!

Every other knowledgeable person (I talked to many, many people) insisted it was a sensor problem and I had spent a MONTH changing everything in the world.

I even had a composition notebook started w/ what I had done, the various code changes I got, How it ran, how long before it would not idle

It was the Two INJECTORS the Whole time!

Need a Bagful of sensors?

I am not a Paid Mechanic (as you can see) I do know Jeep CJs very well (They don't have a computer)

I hope this could be your problem, maybe you can try some used ones prior to buying new ones, just to be sure.

You could just use the excuse that I use to justify getting new parts, whether it's the problem or not---"It's gotten the car to $300,000 miles already, something new is just preventative maintenance. The car is paid for, this is way less than one payment on a new one!"

The Medic
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Tiny
CJ MEDEVAC
Feb 21, 2012.

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