Loss of fuel pressure after priming fuel line
 

I just recently installed a dual walbro 255 fuel pump setup. I am using -6 AN fuel lines from the fuel filter to the OEM S4 TII fuel rails, -6 AN from fuel rails to Aeromotive A1000 FPR, and -6 AN fuel lines from Aeromotive A1000 FPR to OEM return line. I have 550cc primary and 1600cc secondary injectors.

When I turn the key to the on position and prime the fuel system the fuel pressure gauge jumps up to 45psi. While the key is stil in the on position and the fuel pumps turn off after 3-5 second prime phase the fuel pressure drops to 0psi immediately. None of the AN fittings are leaking fuel. Is this common? Do the Walbro fuel pumps have check valves in them? Any and all ideas welcome...

No one with knowledge?

That's normal. Pumps need to be running to maintain pressure.

-Andy

Completely normal.

I called and spoke to an Aeromotive engineer when I had the same question. Apparently holding fuel pressure for 20 mins is an emissions requirement. OEM units do it because they have to.

Ok I will update after I get the ECU back to test the fuel system. Thanks for the advice.