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1989 GMC 3500 runs then wont re-start for a while


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75martin
New User

Nov 3, 2022, 4:25 PM

Post #1 of 5 (1647 views)
1989 GMC 3500 runs then wont re-start for a while Sign In

We have a 1989 GMC 3500 V8 350 dump truck that will start, runs great, but then after turning it off, will not restart until it sits for about an hour. It will crank and crank, turning the engine over, until it runs the battery down, but won't start again. We have replaced the fuel pump and it is getting gas in the carburetor. It just won't fire up after it's been running for a half hour or so. Any advise as to where to go from here would be greatly appreciated.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Nov 3, 2022, 4:53 PM

Post #2 of 5 (1642 views)
Re: 1989 GMC 3500 runs then wont re-start for a while Sign In

Carburetor?

Your truck doesn't have a Carb.

Here are the test procedures.

All "crank, no start" conditions are approached in the same way. Every engine requires certain functions to be able to run. Some of these functions rely on specific components to work and some components are part of more than one function so it is important to see the whole picture to be able to conclude anything about what may have failed. Also, these functions can ONLY be tested during the failure. Any other time and they will simply test good because the problem isn't present at the moment.
If you approach this in any other way, you are merely guessing and that only serves to replace unnecessary parts and wastes money.



Every engine requires spark, fuel and compression to run. That's what we have to look for.

These are the basics that need to be tested and will give us the info required to isolate a cause.

1) Test for spark at the plug end of the wire using a spark tester. If none found, check for power supply on the + terminal of the coil with the key on.


2) Test for injector pulse using a small bulb called a noid light. If none found, check for power supply at one side of the injector with the key on.


3) Use a fuel pressure gauge to test for correct fuel pressure, also noticing if the pressure holds when key is shut off.



Once you have determined which of these functions has dropped out,
you will know which system is having the problem.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



75martin
New User

Nov 18, 2022, 11:40 AM

Post #3 of 5 (1566 views)
Re: 1989 GMC 3500 runs then wont re-start for a while Sign In

Hello again. We have replaced the fuel pump, the battery, the coil, and had the condenser tested. All these are good but we still have the problem. Should we now replace the fuel injectors? We don't know how to test them, Thanks again.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Nov 18, 2022, 11:46 AM

Post #4 of 5 (1563 views)
Re: 1989 GMC 3500 runs then wont re-start for a while Sign In

OK, if you intend to ignore our instructions and keep throwing parts at it, then I'll just go ahead and close this question.

We don't diagnose cars by throwing parts at them.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Nov 18, 2022, 1:08 PM

Post #5 of 5 (1552 views)
Re: 1989 GMC 3500 runs then wont re-start for a while Sign In

? Age and a work truck no doubt. I didn't see a new fuel filter on that parts tossing frenzy. Is it OE or altered or don't know?

As suggested already it starts then long time will repeat. That's suggests fuel not being delivered to me.

It should momentarily fire up with starting fluid so forget spark problem for now if that works right away focus on why and fix it.

Problem with parts tossing is both a waste of $$ but you believe it's not a bad new something. If when you do more than one thing if only guess like this do one at a time.

Better to test things out it's old so what work trucks that old who knows how much has already been done or multiple times that old?

Tom







 
 
 






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