Chasing a fuel issue

[andrewb70]

Here's what I got. Stainless tank from Rick's, A1000 fuel pump (exterior mount), 2 filters, -10 feed line, -8 return line, Aeromotive regulator all going to an EFI 440. Everything is new and the pump has been rebuilt. The car fires up fine, after 5 minute warmup I take her out. Car dies because the fuel pressure starts fluctuating from 59psi down to 25 psi. I've had this problem before thinking that my charge wires from the alternator to the battery were too small...which they were. I've corrected that with 2/0 wires but the problem is still there. Nothing is kinked and the filters are fine. I'm just wondering after 5 minutes with another 2 minute drive, the fuel pump starts to fail. I have a fuel pump controller I can slap on but would that make a difference?

How is the fuel pump wired now?



Andrew

[J-440]

Per instructions. I have it wired to a 30amp relay then straight to the battery. But why does it only do this after the car is warmed up?

[andrewb70]

....But why does it only do this after the car is warmed up?

That, indeed, is the $64k question!

Is there a difference based on how much fuel is in the tank? I am asking this because I have seen in past years various threads about the A1000 pump being too much for most applications, mostly at idle. So what tends to happen is at low load (5 minutes of warm up) most fuel is being bypassed back to the tank. This fuel is heated as a result of going through the pump and the rest of the fuel system (picking up engine heat along the way).

So if there is little fuel in the tank, the problem will present itself sooner. If the tank is full, the problem may not happen as quickly, or at all.

This is also the reason I am not a fan of those huge external pumps and why Aeromotive came out with the pump controller that you mentioned.

There could be other issues, but this is where my brain took me first.

Andrew