Since I have bought my car, it has been hard to start when it is hot. I just recently put a fuel pressure gauge on the rail and as soon as the fuel pump primes, it starts on its way to zero. It takes maybe 3 seconds to go from 45 to 0. I have new injectors and a new AFPR that is going on this week, also deleting the cold start injector. What else could it be other than that if those parts don't fix it? Could there be something up with the fuel pump?

 

Most likely your diaphram in the fuel pressure regulator is ripped and allowing fuel to leak into the intake, flooding out the motor. Change the regulator

other wise it could be a leaking injector

To check the regulator pull the vacum line off of it, it any fuel comes out the reg is junk.

 

I dont think the diaphram is torn because there is no fuel that comes out when the car is running. I hope not anyways because my afpr from tpi parts didnt include a diaphram. Where can I get just a diaphram? I just got my injector rebuild kit for some LT1 injectors I had. I also just got the new prom in so they will probably be in within this week, we'll see. I guess if that dont fix it, the fuel pump is next. What do you guys think?

 

Autozone sells the replacement diaphragm and spring for $40, I just replaced mine. If you plan on getting an AFPR, note that none of them except the Holley come with a new diaphragm.

 

yeah they really need to state that in the description.

 

If you suspect the FRP, simply pinch the fuel return line and retest pressure.

 

which one is the return line?

 

I finished replacing the injectors and the fuel pressure regulator and deleted the cold start injector. Diaphram looked great. I guess its time for a pump, right? If I buy a Walbro 255, does the diaphram for it come with it or is that separate? What else could it be other than the return diaphram in the tank?

 

The smaller of the two.