Aeromotive FPR users - Hold Pressure question
 

I'm buttoning up my fuel system and was running through a few tests before I felt all was good. It builds pressure fine. Resistor bypassed. However, after I turn off the pump I expected to see it hold pressure for a while. It bleeds off very quickly. (20 seconds or so) The FSM says that the stock FPR should hold 20psi after 5 minutes.

Just to make sure that it's not leaks or some other plumbing problem, I clamped off the return line and energized the pump. After 5 minutes it was still holding over 40psi, so I'm certain that it's not a leak in the other end of the system.

So my question is, for other Aeromotive FPR users, how long does your fuel system take to depressurize?

I have an Aeromotive FPR, but I'm using a walbro GSS-341 pump, which doesn't have a check valve on its output, so I lose pressure almost instantly.

Even with the stock pump and its check valve, I'd assume that some pressure leaks back through the pump, it's not all about the FPR.

Thanks mks..

I just called Aeromotive and asked. Seems that it's an EPA requirement to hold fuel pressure. It somehow reduces starting emissions. He said it's totally normal, so that's good enough for me.

Guess I should have just called them before I posted..

Well lucky me that sweden is outside of the EPAs jurisdiction =)

hey NewbernD
mine does the exact same as you said
I was wondering the same
thanks for the info

i loose it instantly. using the aeromotive A1000 pump....

Concur with rxrotary2_7.

The Bosch FPR from my previous FD would hold pressure for about 5 minutes.

The pump doesnt matter in this situation - no matter what pump you are using when you turn off the key it will stop pumping and a check valve on one side (as all pumps have I think) of the system doesnt matter. This is a function of your fuel pressure regulator and most, if not all, aftermarket pressure regulators only slow the fuel to a certain point but dont restrict in entirely - therefore it will bleed off any pressure left in the line. As far as an epa regulation to hold pressure, while it may be true, sounds like a load of crap to me. If your fuel tank is sealed then it doesnt make a bit of difference what the pressure in your lines is.

Thanks guys.. It's good to have some additional verification.

It may sound like a load of crap to you but after doing a little more research I believe that the requirement was to help eliminate vapor lock in the fuel lines, and thus hard starts, and thus unburned fuel from leaving via the tailpipe. If you keep the system pressurized it is much more difficult to allow pockets of air/vapor to form.

And no, not all pumps have a check valve.