Will not start after sitting for 12 hours or more. It will start if it only sits 8 hours or less

Tiny
GLGJRCURIOUSG
  • MEMBER
  • 1997 GMC SIERRA
  • 260,000 MILES
If truck sits for 8 hours or less, it cranks right up & runs great. If sits for 12 hours or more. It takes a whole battery to get started. But once running, runs great. Truck has now sat for 3 days. It will not start! I have replaced the. Spark plugs & wires, ditributor cap & rotory button, fuel filter, & cleaned k&n air filter. I can hear fuel pump running when key is turned on. I dont have fuel pressure tester. But I did pull the gas line lose at the motor side of the filter. I turned key and gas squirted everywhere. Whats so werd is. Ive checked the fire. I have fire, & I even squirted starting fluid in carb/throdel body. And nothing, it want hit. I had the timing checked last year. Im stumped & im broke down at home. Please, please. If you have any advice?
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Saturday, August 3rd, 2013 AT 1:23 PM

9 Replies

Tiny
CARADIODOC
  • EXPERT
What do you mean by "it takes a whole battery to get started"? Are you expecting it to start with half a battery, or do you mean you run the battery dead by the time the engine finally starts?

Ignition timing is computer-controlled and not adjustable. That isn't going to change. If the engine runs good at times, you know the timing is okay.

Have you checked for diagnostic fault codes? Many auto parts stores will read them for you for free.
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Saturday, August 3rd, 2013 AT 3:59 PM
Tiny
GLGJRCURIOUSG
  • MEMBER
Yes I mean it runs a fresh battery down by the time it cranks. I had the code read from my check engine light. It said. Random misfire. That was the only code.
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Saturday, August 3rd, 2013 AT 4:15 PM
Tiny
CARADIODOC
  • EXPERT
The place to start is with measuring the fuel pressure. Some GM engines are real picky and will not start or run if the pressure is two pounds below specs. You can verify that by introducing some starting fluid during cranking.
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Saturday, August 3rd, 2013 AT 4:22 PM
Tiny
GLGJRCURIOUSG
  • MEMBER
I tryed starting fluid. It did not help.
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Saturday, August 3rd, 2013 AT 4:35 PM
Tiny
CARADIODOC
  • EXPERT
Sorry; I read that but forgot.

If you removed the fresh air tube to spray the starting fluid in, no air would go through the mass air flow sensor, then the Engine Computer would command no fuel from the injectors.

The next thing would be to connect a scanner to view live data. That will show the injector pulse width and whether the computer is firing them. You have to be missing fuel or spark Where did you introduce the starting fluid?
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Saturday, August 3rd, 2013 AT 5:00 PM
Tiny
GLGJRCURIOUSG
  • MEMBER
Yes I tryed starting fluid in air flow that is on top of throdle body. I opened flap by depresing throdle and sprayed fluid. Is their another place to introduce starting fluid to test fuel problem?
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Sunday, August 4th, 2013 AT 1:53 PM
Tiny
CARADIODOC
  • EXPERT
Nope. If there was spark, compression, and valve timing was correct, it should have run on the starting fluid unless there was so much that it flooded the spark plugs.
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Sunday, August 4th, 2013 AT 2:18 PM
Tiny
GLGJRCURIOUSG
  • MEMBER
I wanted to contact u once more to thank you for all your time and help. I'm still stumped on my truck. I don't have a way to test fuel pressure. That has to be the problem. But befor I start replaceing something that is so hard to replace like a fuel pump. I have to be sure. I'm haveing a wrecker pick my truck up this evening and carrying it to a mechanic. I wanted you to know that you were a big help. Thank you for your time and help! I will give you guys a great reference to everyone I know. Thank you sincirely: george
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Monday, August 5th, 2013 AT 10:00 AM
Tiny
CARADIODOC
  • EXPERT
Thank you for the kind words. I wish I could have come up with a better answer. I'm confused about why it wouldn't run on starting fluid. We know compression and valve timing aren't the cause of the no-start because the engine does run at times, and those things won't change back and forth. We know you have spark. That leaves fuel or soaked spark plugs.
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Monday, August 5th, 2013 AT 10:42 AM

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