Fuel Pressure

Hi everyone, Happy New Year. Well I have a problem with my mustang. When I go to start it, it cranks over like the fuel pump isn't initializing the pressure.

The problem is that when I looked at my guage under the hood when my buddy turned the key on it went to 40psi immediately, but as soon as the pump went off it went back down to zero immediately.

I know the system is leaking somewhere, and I suspect a bad fpr because it is an old crane unit. Any help would be greatly appreciated, as I do not want to burn up my brand new 190lph fuel pump.

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88GT stock shortblock, ported GT-40 iron heads, ported Edlebrock Performer intake, 24# inj, Pro-M 75mm Bullet MAM, 3.73, hurst short throw, F-303, electric fan, alum rad, FMS HD clutch, R134a ac conversion, 70mm TB , and some other stuff I probably forgot, best run so far on ET streets is 13.02@106 with a 1.87 60ft.