Hey all,

My truck cranks up in 2 secs first thing in the morning but during the course of the day when it is hot, it takes anywhere from 10-20 secs to crank up. I have replaced the fuel sending unit with inline fuel pump, filter before and after high pressure fuel pump. When I checked the fuel pressure one time, it was around 33 PSI. Is that normal? My last resort is to replace the high pressure fuel pump. I bought a Universal Walbro 255LPH Inline Fuel Pump (GSL392-AN8) and about to install it. Seeking some advise before I replace the fuel pump. Hope the new pump will not hurt the old stock FORD EFI system.

 

I am assuming you have a 302 fuel injected truck?

You need to test the pressure when the truck is hot before you get ready to start it. The pressure usually runs around 39 psi give or take. I would get the engine hot while reading the pressure, and then let it sit the required time and watch the pressure. If the pressure drops, then you have a leak in the system. There are 3 places for it to leak;

The check valve in the pump

The pressure regulator

A leaky injector or injectors.

If you find the pressure is leaking down, then pump it up again and then take some needle nose pliers and pinch the supply line closed right after you turn the engine off. If that stops the pressure dropping you know you have a problem with it leaking back through the check valve in the pump. I suppose it's also possible the switching valve could be leaking if you have dual tanks.

If you find pinching the supply line does not stop the leaking, then pump it up again and pinch the fuel return line. If this stops the leaking then the fuel pressure regulator is leaking.

If neither one of these stops the leaking, then you have a leaking injector or injectors.