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Truck will not start

Tiny
NICHOLS2236
  • MEMBER
  • 1990 GMC C1500
  • V8
  • 2WD
  • AUTOMATIC
  • 170,000 MILES
It is getting fuel and spark but will not start.
Monday, January 31st, 2011 AT 11:32 PM

18 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,170 POSTS
Either you are not getting a hot enough spark, the fuel pressure is too weak, the timing is off, or the engine has low compression. Check all those items and let me know what you find. Note: The spark should be a good hot blue snapping spark. Also, make sure the injectors are getting power. See if it will start with starting fluid for a few seconds. If it does, then it sounds fuel related.

This guide will help you

https://www.2carpros.com/articles/car-cranks-but-wont-start

Please run down this guide and report back.
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Monday, February 7th, 2011 AT 7:49 PM
Tiny
VANMAN13760
  • MEMBER
  • 1 POST
After putting up with a similar problem for a year, it turned out there was moisture got into the computer, and it affected the pigtails plugging into it. Finally the mechanic relocated the computer to behind the driver’s seat, it was behind the kick panel at the bottom of the drivers side door, my 1990 GMC runs like a bear now. John C.
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Saturday, May 19th, 2018 AT 9:05 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 42,877 POSTS
Oh yes, moisture causes many problems. Good find though. Great addition to this thread! Please feel free to help out whenever you are on the site. :)

Cheers, Ken
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Monday, May 21st, 2018 AT 10:43 AM
Tiny
MAYTAGE
  • MEMBER
  • 8 POSTS
  • 1990 GMC C1500
  • 5.7L
  • V8
  • 2WD
  • AUTOMATIC
I'm not getting any fire when trying to start my 1990 GMC 1500. It will not start. I have replaced the coil, the ignition module and checked all the fuses, everything is good. When I stopped to get gas, the truck started, drove about 2 miles and stopped and would not start back up. When I pour gas into my fuel injector, it will start and run about 10 seconds but no gas is coming out of the fuel injectors. Now there is no spark when I take the distributor cap wire off.
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Thursday, April 30th, 2020 AT 10:50 AM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,170 POSTS
Some stupid questions. Have you checked main fuses under the hood? Can you hear the fuel pump run for a couple seconds when you first turn the key on?

Here is my present theory based on your description. Your vehicle is equipped with an auto shut down relay. In the event of an accident, roll over. This relay will shut off power to the fuel pump, injectors, and ignition.

Often times, if there is a short in the system, say for example the fuel pump, it will trigger the ASD to shut down the engine. Since you had spark with no fuel at first, and then you lost the spark, something is telling me there is a short with the fuel pump which resulted in the ASD actuating.

Starting about 1990, the ASD relay was in a plastic under hood relay box at the left fender well. Most of them have a reset switch. Locate that, see if you can reset it, and see if there is a change.

Let me know what you find.
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Thursday, April 30th, 2020 AT 10:50 AM (Merged)
Tiny
MAYTAGE
  • MEMBER
  • 8 POSTS
Thanks for replaying, I will let you know.
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Thursday, April 30th, 2020 AT 10:50 AM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,170 POSTS
Glad to help.
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Thursday, April 30th, 2020 AT 10:50 AM (Merged)
Tiny
MAYTAGE
  • MEMBER
  • 8 POSTS
That did not help.
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Thursday, April 30th, 2020 AT 10:50 AM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,170 POSTS
Are you getting power to the ASD?
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Thursday, April 30th, 2020 AT 10:50 AM (Merged)
Tiny
GATESJ
  • MEMBER
  • 2 POSTS
  • GMC C1500
My GMC Suburban 1500 will not start. I put the key in to start it up but the truck appears to be dead, no power. The daskboard lights did not com on and there is no sound whatsoever. It did this on me twice but started up within 3-5 minutes. When the truck did start up the clock went back to 12:00 as if the battery had been disconnect and the computer reset itself. I heard a clicking sound behind the dashboard then it stop and I was able to start the truck. My wife was driving the truck today and it happen again and it will not start for her and I am at work and I will have to go get it later. What could this be? Is it a relay problem of some sort?

Thanks for your help.
James
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Thursday, April 30th, 2020 AT 10:50 AM (Merged)
Tiny
HOTWHEELSGMC
  • MEMBER
  • 31 POSTS
Sounds like it could be a short in the ignition, or coil. Something to do with your charging system.
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Thursday, April 30th, 2020 AT 10:50 AM (Merged)
Tiny
GATESJ
  • MEMBER
  • 2 POSTS
You were right, it did have something to do with my charging system. I went to get my truck yeterday and was about to try a jump start with my other car. Another gentlement saw me and ask if I would like to use his jumper starter kit instead of jumping from another car. When I clamp the positive cable on my battery in the truck, the hood light came on but the ground cable had not been clamp to anything. I disconnected the positive cable and attemped to start my truck, it started right up. I turned it off and wend to check under the hood, the hood light had gone off. I check the battery cable connection and sure enogh the positive cable that runs to the battery was lose and I realized that depending on wht way the truck was setting there would be just enough connection to the battery to start the truck. Everything appears to be okay.

Thanks again for you help. I will remember you guides when I need car parts and advise. Do you guys have any affiliations in Northern Virginia, (Leesburg, Virginia)?
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Thursday, April 30th, 2020 AT 10:50 AM (Merged)
Tiny
CARLYLE 1
  • MEMBER
  • 3 POSTS
  • 1988 GMC C1500
Engine Performance problem
1988 GMC C1500 6 cyl Two Wheel Drive Automatic

I have 1988 Gmc with a 4.3 L engine will not start new plugs, wires, cap and rotor, and module. Has no spark, and no fuel at the injectors but there is power to the injectors. It has throttle body injection. Fuel in the lines when turning over but will not start was running before. And runs smooth when running just a matter of getting it started.
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Thursday, April 30th, 2020 AT 10:51 AM (Merged)
Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
Welcome to the forum, Is the coil in the cap? If so check B+ terminal at the cap for voltage, pink wire, goes hot when you turn on the key. There is probably a tach terminal next to it, use a testlite on that terminal, the lite should pulse.

The purple wire with white tracer, goes from the distributor to pcm, carries rpm signal, engine cranking, there is a pulse on that circuit, without that signal, no injector pulse, the pcm controls injector ground.

With the bypass ignition system, during cranking, the computer doesn't control spark timing, the ignition module does. If everything else checks out, check the pickup coil. Also, are there any trouble codes?
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Thursday, April 30th, 2020 AT 10:51 AM (Merged)
Tiny
CARLYLE 1
  • MEMBER
  • 3 POSTS
The coil is seperate but should be same set up right?
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Thursday, April 30th, 2020 AT 10:51 AM (Merged)
Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
Yes, B+ and negative side of coil, goes hot with the key on. With testlite on negative side, the lite should pulse, engine cranking. If no pulse, the ground isn't being switched for some reason.
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Thursday, April 30th, 2020 AT 10:51 AM (Merged)
Tiny
CARLYLE 1
  • MEMBER
  • 3 POSTS
Hooked up test lead to rpm lead off coil it lights up but does not flash when cranking. The purple one does not either on the distributor. I don't have a scan tool, but I am sure ther is antoher way I can read the codes by useing a jumper wire
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Thursday, April 30th, 2020 AT 10:51 AM (Merged)
Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
You may not be able to use a testlite on the purple wire? If you have dmm with a tach setting, that should give reading? Right now, my thought is something wrong with the pick-up coil. I have heard of using flashlite battery, 1.5 volt, to trick the ignition module into thinking it is receiving a signal from the pickup coil, with the key on, it may cause a spark. Don't get bit by secondary ignition voltage, it never hurt me,but, always surprises me. I don't like it.

Yes, you can check codes using a jumper wire.


https://www.2carpros.com/forum/automotive_pictures/170934_aldl_35.jpg

, you place jumper between terminals A & B, turn the key on, no crank. The check engine lite starts flashing, you count the flashes to get the codes, two digit codes. A code 12 is one flash, slight pause, two quick flashes. It may repeat code three times before moving to the next code, if there are any?
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Thursday, April 30th, 2020 AT 10:51 AM (Merged)

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