This is topic Need late model chevy help... in forum Tech Talk at Northern California Ford Owners  .


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Posted by blind (Member # 3052) on :
 
I was driving at 50mph, the truck suddenly just died, no abnormal sounds just died, I didn't notice it until I noticed that the throttle wasn't doing anything.

I have checked the following:
I am getting 60psi KOEO at the fuel rail
I am getting spark (verified by pulling plug wire and holding to ground)
spark plugs were wet and black, I replaced all of them with new autolites.
I did the diagnostic test on the fuel injector coil, and it is pulsing when engine cranks.
starter cranks, I'm getting fuel, I'm getting spark...but it wont start!!

Does anyone have any ideas?

Truck is a `97 vortec 4.3L V6 automatic GMC Sierra with 123k miles.


I realize this is the wrong place, but I will take any help I can get on this [Frown]

oh I forgot to mention there are no codes in the computer, but when hooked up to a tap it is giving data, I varified the TP sensor voltage using the tap on the computer...
 
Posted by mtbaughs (Member # 4052) on :
 
Sounds like you have an ignition problem somewhere. If the plugs are soaked than at one point in time your injectors were sending fuel and your ignition wasn't sending spark. I've seen spark at the wires when there is an issue with an ignition driver. I don't know what it is on a chevy. A module of some sort that says to the coil or coil pack fire this cylinder in this order according to engine postion. Maybe something along the lines of a cam position sensor or crank position sensor that maybe took a dump on ya. I'd verify that you are getting signals on those if they are present.
 
Posted by Black94 5.0 (Member # 655) on :
 
What's the fuel pressure when you crank the engine?....2 weeks ago I helped my friend with his 97 GMC 4.3 Vortec...It would register 60psi fuel pressure, then it would drop as soon as you try to start it...It turned out that the fuel pump pick up line was cracked in the tank and the pump wasn't giving enought fuel when needed....

I'd re-check the fuel delivery and spark output, because if the starter cranks and you have fuel and spark the engine should start....

The only thing left to assume is that your timming is off...
 
Posted by mtbaughs (Member # 4052) on :
 
I'm curious what this ended up being. Let me know when you've got it figured
 
Posted by blind (Member # 3052) on :
 
fuel pressure while cranking is ~56psi...

I have a hunch, a few months ago I removed my MSD 6A from the truck because it did the SAME EXACT thing to me, the truck wouldn't start, it would try to catch and would sound like the timing was 180degree's off when cranking, I pulled the MSD and the problem went away...until now.

I'm going to hook an MSD back up to the truck tomorrow, I figured the MSD just went bad or something but I geuss not?

What controls the signal to the coil? The coil must be good because I am getting a strong spark, but maybe the spark timing is just way off?
 
Posted by blind (Member # 3052) on :
 
truck runs again, it was the coil [Confused] [Confused]

Runs like shit though and is now throwing a code, I think the plugs I replaced with either the wrong gap was used or they are the wrong plugs.
 




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