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Steve, ASE L1 Master Technician
Category: GM
Satisfied Customers: 5494
Experience:  25+ Years experience as a professional working automotive technician; ASE L1 master technician
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cold start problem,on a 98 5.7 vortec , got spark,and gas

Customer Question

cold start problem,on a 98 5.7 vortec , got spark,and gas
Submitted: 7 years ago.
Category: GM
Expert:  Steve replied 7 years ago.
The fuel injector assembly used on this engine is well known for being very sensitive to fuel pressure variations. The injector must have a very minimum of 60 PSI of fuel rpessure present, or the injector poppet valves will not open, causing the engine to not start. Even 59PSi would not be enough, pressure MUST be in the 60 to 66 psi range.
I would suggest connecting a fuel rpessure gauge to the test port located on the fuel line at the drivers side rear of the engine. Then, after the truck has been sitting overnight, take a look to see what the pressure reading is; you should have very close to 60 PSI, and when the key is cycled to start you must have 60 PSI or over. If not, you will need to locate the cause of the loss of fuel pressure when the engine is off. The most common cause of a pressure loss while the key is off would be back into the tank through an internally worn fuel pump.