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#1
09-20-2006, 05:49 PM
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96 Yukon 5.7 won't start cold unless primed
Having a problem getting the engine to start after it has set for a while. Starts after it it has run whether it is hot or still cold. Just have a hard time starting it after it sets for half a day or more. I have to use starting fluid and it starts immediately. I can hear the fuel pump cycle and stop when the key is turned on. The problem seems fuel related, but I don't know where to begin. Cycling the key on and off doesn't help get it to start, just thought this might help get things primed so I can go. Keeping a starting fluid can handy is growing old, especially since cold weather is on it's way. Thanks all.
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#2
09-20-2006, 09:24 PM
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Re: 96 Yukon 5.7 won't start cold unless primed
A leaking fuel pressure regulator, leaking injector(s) or a bad check ball in the fuel pump can cause your situation.
You should check the fuel pressure and watch what it does when you turn the engine off. If it drops to zero, something is leaking fuel into the engine causing your hard start issue. Fuel pressure regulator leaking is very common. //2000CAYukon
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#3
09-21-2006, 12:11 PM
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Re: 96 Yukon 5.7 won't start cold unless primed
I had a '97 k1500 5.7 that did the same thing ended up being the coolant temp sensor.
__________________
NO 4 N JUNK  1994 GMC K1500 XC 5.7L 2008 Chevy Impala LTZ
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#4
09-22-2006, 07:55 AM
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Re: 96 Yukon 5.7 won't start cold unless primed
I'll investigate the pressure regulator and fuel pump.
A little more investigation looks like these two components are quite a task to replace. The regulator inside the plenum and the pump, the last place you want to go.
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#5
09-22-2006, 09:18 AM
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Re: 96 Yukon 5.7 won't start cold unless primed
One of two things could be going on here
1. Fuel pressure...this truck needs 60-66 psi to start and run..if the fuel pressure is less than 60, it will not start. 2. Injector poppets my be stuck closed. this will cause a hard start/no start condition cold (also a cold misfire) Now with the injectors, you cannot clean them convetionally, there is a special procedure for this...I have posted the procedure many times before, do a search and you should be able to find it
__________________
Why do you never have enough time or money to do the job right the first time, but enough time and money to do it again? Got all the certifications 25 years ASE Certified Master Technician GM WCT Yea..I work at a DEALERSHIP....got a problem with that? Want to diagnose cars like the Pros? FOR SALE: OTC Perception 2 channel Labscope (badged as a Matco Reality) This is my personal labscope that I use to diagnose waveforms, like new, comes with leads and training video PM Me for details
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#6
09-22-2006, 03:16 PM
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Re: 96 Yukon 5.7 won't start cold unless primed
Here is the scoop.
It was the pressure regulator. What a job. It is under the plenum and takes about 5 hours to replace. There are about 12 electrical connectors to unplug, a dozen bolts to remove, fuel lines, and wrestling with the electrical wiring while trying to lift off the plenum. Once there, the reg is held by a snap clip that takes about 30 seconds. Someone's stupid clever idea to stow this away. Immediate result, the pump can be heard building pressure when the key is cycled. The pump does not run for a full prime when the key is cycled because the line is holding pressure. Before the pump would run 5sec with the same sound and the same length of time when the key is cycled. I'll update if there is any more issues. Reg $65 Gasket Set $25 Carb Cleaner $5 Time 4-5 Hours and a stiff back. (some folks may be faster)
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