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Vladgmru
Vladgmru, Automotive Electrician
Category: Chevy
Satisfied Customers: 2519
Experience:  I've been working with American made cars since 1992.
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1993 GMC: k1500..when cold but when the truck warms up it will stall

Customer Question

I have a 1993 GMC Sierra k1500 4.3 v6.
The truck will start and run when cold but when the truck warms up it will stall while driving. I've let the truck run at idle for over an hour one night and the truck never stalled. But when I am driving it will stall after warm and about an hour after cold start. After stalling the truck will not start again until it is cold. 2-3 hrs.
Don't wanna throw parts at the truck. Really can't afford to.
Submitted: 4 years ago.
Category: Chevy
Expert:  Vladgmru replied 4 years ago.
HelloCustomer
Thanks for choosing JustAnswer.
My name is Vladimir.
Is it a TBI ( 2 big injectors) engine?
What is the 8th digit of your VIN #?
Please reply back to this thread.
Customer: replied 4 years ago.
yes 2 injectors and the 8th vin is Z
Expert:  Vladgmru replied 4 years ago.
Thanks,
You should check if you get spark from the ignition coil when it won't start.
If you get spark, then check if your injectors spray fuel.
If you do not get spark from the ignition coil, then your ignition control module or pick-up coil ( inside the distributor) could be a reason. These parts may fail to operate when they get hot.
Please let me know about you findings and we will continue troubleshooting.
Let me know if you have more questions.
Vlad.
Customer: replied 4 years ago.
I forgot to tell you that. I have sprayed starting flued into the intake when it has done this and when i crank the motor it will sputter for 4 -8 seconds depending on how much starter fluid. So I would think it has to be getting spark right.
Expert:  Vladgmru replied 4 years ago.
If it starts or is trying to start and run when you spray starting fluid, then you probably have a faulty fuel pump that does not supply fuel to the injectors.
I do not think we should guess, next time it happens please check for spark with a spark tester or an old spark plug and if you get a good spark, then see if your injectors click and spray fuel.
Let me know.


Edited by Vladgmru on 1/6/2010 at 11:17 AM EST
Customer: replied 4 years ago.
I can hear the fuel pump turn on when the key is turned. Even after it dies. And if the truck tries to run when starting fluid is sprayed wouldn't there have to be spark. With no spark it wouldnt try to start...
This only happens when truck is warm and driven for a period of 30 min to an hour. Then it takes 3-5 hours b4 the truck will start again. (cold start)
Expert:  Vladgmru replied 4 years ago.
Ok, if it gets spark and fuel , then it should run unless it has a clogged catalytic converter or a timing issue. If you hear the fuel pump, that does not automatically mean it supplies fuel.
I have seen a partially glogged catalytic that prevents exhaust gases to pass through when it gets hot.
Sir, you should determine what you truck is missing when it does not star during that 3-5 hours period.
I used to check and recheck everything, it is not a good idea to guess or assume when it comes to troubleshooting such intermittent problems.


Edited by Vladgmru on 1/6/2010 at 11:38 AM EST
Customer: replied 4 years ago.
But what I mean is if the fuel pump is bad wouldn't it eventually not start at all. Like this truck only doesn't start after it dies. But will start again when COLD
Expert:  Vladgmru replied 4 years ago.
A faulty fuel pump may fail to supply fuel after prolonged operation, then after cooling down it may operate correctly again.
Customer: replied 4 years ago.
So you deff think it's the pump. Not a relay or anything else.
Expert:  Vladgmru replied 4 years ago.
It could be anything, that is why I asked you to check for spark and other things in my first answer.
I do not want you to change parts by guesswork, I want you to check what is missing when it won't restart. After we have such information, we can move further.
Please take a time to re-read this thread from the beginning.
Customer: replied 4 years ago.
Yes I understand about getting spark but I kno it is getting spark because the truck will kick over when starting fluid is sprayed into the throttlebody. But I just don't understand y it only accurs after the truck up to temp for more than 20 min while driving. But it seems it will run forever if just sitting at idle.
Expert:  Vladgmru replied 4 years ago.
Ok, let's finish with it.
I have to know if the injectors spray fuel when your engine won't start after stalling.
I can't give a correct answer without such information.
Regards,
Vladimir.


Edited by Vladgmru on 1/7/2010 at 7:25 AM EST
Customer: replied 4 years ago.
Hey when the truck dies it does get spark but the injectors are not squirting fuel. But is it common for a fuel pump to shut off after running and driving for an hour but then work again after sitting for 3-5 hours?
Expert:  Vladgmru replied 4 years ago.
Hello,
Yes it does happen that a fuel pump stops supplying fuel after prolonged driving and then works again after cooling down.
You should also verify if you get impulses to the injectors.
You will need a NOID LITE to check if your injectors get pulsed. If your noid lite is blinking while you are cranking the engine, then you definitely have a problem with the fuel supply.


Edited by Vladgmru on 1/9/2010 at 6:44 AM EST
Customer: replied 4 years ago.
Hey I hooked up a noid light to the injector harneses and after the truck dies the light does NOT light up. So I'm guessing that means there is no power going to the injectors after the truck dies.
Expert:  Vladgmru replied 4 years ago.
Hello,
It sounds that the Engine Control Module do not operate the injectors. The ECM provides ground pulses to the injectors when it sees an ignition reference signal from the ignition control module. It appears that your ignition control module ( inside the distributor) fails to send reference pulses when it gets hot.
First of all, make sure you get +12v power from the ignition switch on the Red and White wires at the injectors connector with the key ON.
If there is +12v power to injectors, then there is definitely no ground to the injectors from the ECM.
I would replace the ignition control module.
Let me know how it turns out.
Vladgmru, Automotive Electrician
Category: Chevy
Satisfied Customers: 2519
Experience: I've been working with American made cars since 1992.
Vladgmru and 11 other Chevy Specialists are ready to help you
Customer: replied 4 years ago.
Thank you very much. I replaced the ignition control module after letting the truck die and it started right back up and runs fine. No more dying.
Expert:  Vladgmru replied 4 years ago.
You are welcome!
I am glad to hear that we have finally figured it out.
I would like to also notice that we have faced with an unusual failure when your ignition control module did trigger the ignition coil ( you had spark), but failed to send reference signals to the PCM at the same time.
Hope you installed an original AC Delco module.
Thank you very much for accepting my answer and the bonus.
Would be glad to help you again.
Regards,
Vladimir.


Edited by Vladgmru on 1/15/2010 at 8:56 AM EST

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Vladgmru
Vladgmru
Automotive Electrician
305 Satisfied Customers
I've been working with American made cars since 1992.