1999 Tahoe no start

[SunlitComet]

Well the battery is new. And as far as fuel pressure goes with the key on it holds 60psi when the key is of it holds between 50-60 psi for about five minutes or so and slowly drops down to zero over the corse of about 5 hours. An it cranks but won't turn over but when I let off it try's to run.

It sounds like your pump may be just fine. Perhaps you should check the outputs of the various ignition switch to ensure each output operates as it should in each key position. Specifically the pink wire output wire. This would effect normal operation of the pump as it entirely controlled by the PCM. If it turns on and primes when moved to on it is possible then when you move it to start the contacts in the switch break the currents flow and kill off the pcm and other engine electronics. Until you let off. Just one thing to look at.

 

[Dillonv2008]

I'm just saying my buddy had problem in his Denali. He had hard time starting and get idle unless you sprayed carb cleaner in throttle body and found out it was fuel pump n evap box by gas tank to.