Hot start issue
 

I'm having a hot start issue. 02 SS 9000 miles. Starts right up in the morning after sitting overnight, however once it is fully warmed up and parked, it will crank for at least 5 seconds if its sits between about 30 minutes up to 8 hours then it finally starts, stutters for a second and then everythings fine. If I restart it before 30 minutes it will start ok.
It is not the starter or battery because it turns over fast when I try to start it. Car is pretty much stock besides a slp lid and air filter and a cat back exhaust.

test fuel pressure

Ok, when i turn the key to on with the engine off fuel pressure jumps to 60psi, then when i hear the fuel pump click off the fuel pressure drops to zero within about 10 seconds. With it running pressure is steady at 60.
After driving the car and getting it fully warmed up then parking it in 100 degree heat and waiting an hour so i can replicate the issue, heres what happens.
With the fuel pressure tester hooked up and turning the key to on i get about 10 psi, key off and on again goes up to about 30 off and on again goes up to 60. Then ofcourse it starts right up.
I then shut it off and notice the fuel pressure takes much longer to go down about 5 minutes to get to zero. I also noticed the fuel rails were very hot so im thinking the fuel turning into vapor as soon as it hits the heat soaked empty fuel rails has some play in this issue. I restarted it and let it run for a few minutes to let the flow of fuel cool the rails down (still not as cool as after sitting overnight in cooler temps, though) and then shut it off, this time the fuel pressure dropped much quicker about a minute to get to zero. My guess is the issue is caused by the pressure regulator or anti drain back valve (is there one on these cars?) on the fuel pump, and the reason it does this when hot and not when cold is when the fuel hits the hot fuel rails it turns to vapor before it hits the injectors for a few seconds while its cranking. If it held pressure the fuel in the fuel rails would act as sort of a heatsink and keep the fuel from boiling before it hits the injectors. Why the fuel pressure takes longer to go down when hot is still a mystery, though. I could be wrong but thats my guess.
So what is the verdict here getting a new fuel pump? about how much would a shop charge to do this (yes i know the rear end has to be dropped to get the tank out)

Just a suggestion, why not add a temporary pushbutton to activate the fuel pump relay?
Then you could hold button, for say 15 seconds, or however long it takes, your choice, and attempt to start.

It would prove your theory.

It makes no difference how long you wait you have to cycle the key off and on a few times to get the fuel pressure to rise on a hot restart.

fuel pump or fuel pressure regulator is going or gone.

That's what I figured, got a quote today $850 plus tax to replace the fuel pump with a new Delphi unit. Looks like that's what I'm going to do.

New fuel pump installed problem solved car starts up with just the tap of the key now. I was surprised at how quickly they were able to repair it too i dropped the car off 3 hours later got a call saying its done which seems pretty fast considering the work involved. Thanks for the help guys.

well i wonder if they cut a hatch in it. have a look under your carpet over the gas tank in the back

Thats exactly what i thought too but nope, no hatch.