Chasing a fuel issue

[J-440]

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?

[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

[J-440]

That makes total sense. I only have about 5 gallons in the tank. I do have the lines insulated as best as possible. But with an iron block and headers, she still puts out a lot of heat. Would that FP controller solve this issue though?

[andrewb70]

That makes total sense. I only have about 5 gallons in the tank. I do have the lines insulated as best as possible. But with an iron block and headers, she still puts out a lot of heat. Would that FP controller solve this issue though?

I would first top off the tank and see if the problem is delayed or eliminated. If that helps, then we know we are on the right track.

I would not be introducing another variable into the equation at the moment. Make one change at a time and try to isolate the problem. Otherwise, you're going to be chasing your tail!

Andrew

[J-440]

I hear ya. Hey man, thanks for the help. Gonna see what I can do.

[andrewb70]

I hear ya. Hey man, thanks for the help. Gonna see what I can do.

Keep us posted.

Andrew

[J-440]

Well I installed the fuel pump controller but I’m not getting a signal from my tach. The directions say to hook the wire up to the negative side of the coil. I rechecked the wire to make sure there were no rips or tears, used a multimeter and even a jumper wire. Nothing. And why the negative side? Shouldn’t the tach signal be on the positive side of the coil? The controller is working bc I can hear the pump speed drop after a few seconds, just no tach signal.

[andrewb70]

Well I installed the fuel pump controller but I’m not getting a signal from my tach. The directions say to hook the wire up to the negative side of the coil. I rechecked the wire to make sure there were no rips or tears, used a multimeter and even a jumper wire. Nothing. And why the negative side? Shouldn’t the tach signal be on the positive side of the coil? The controller is working bc I can hear the pump speed drop after a few seconds, just no tach signal.

The tach signal always comes from the negative side of the coil because that is how the coil is triggered. Positive always on and at the right time the ground is triggered to get spark.

Andrew

[J-440]

Good info, thanks. Guess I’ll be sending it back and see what they can diagnose.