[Dusten]

Are you tuned for the pumps? Does the tune have 12v full time for the pumps? Did you upgrade your return line?

 

[Dusten]

It is definitely not setup for 12v constant, because when I bypassed the resistor to see if my original pumps were bad, the pressure went up to 43psi. The problem was, when I rev it up not even in gear, the pressure would drop to 35 and lean out. The truck would start and run great up to 1/4 throttle.

Lightning performance said i should bypass the resistor, so I left it that way. Now I have 68psi at idle, and it just dies. Makes great power wot, will leave a 50ft posi burn out now, but won't idle. Both o2 sensors are stuck at almost 1v now, and I have cel rich both banks

Someone said I should put the resistor back in. The fuel rail is stock, not sure if it is the same system as the lighting? This is an 03 harley. It is the same system as my 2000 expedition. I bought a rolled 03 harley and put the supercharger on my 00 expedition, but that truck only has a single pump and runs fine. This 03 is the one with the issue though.

Having lfp tune your truck is stupid

The 255's are over running your regulator and return. This is very common.

The return line isn't flowing enough fuel back to the tank.

 

[Dusten]

If you still have those pumps the only fix is upgrading the return line.

 

[Dusten]

No. The resistor is completely bypassed by the computer when it chooses.

The resistor only works at low load. It's job is to drop voltage from 12 to 7.5 to slow the pumps down. This is why at idle with the resistor everything is fine.

Once at a certain load and throttle position the resistor is bypassed by the truck and the pumps receive 12v. This is why above 1/4 throttle or without the resistor you're having issues. On come trucks the return line just isn't sufficient for the volume of fuel the truck is seeing. The only fix is a larger return line. Or OEM pumps. You pick.

 

[Dusten]

With it removed and 68psi that's as expected because you're increasing output without increasing demand. I guess I read it wrong

Basically you out those pumps in and were not tuned. Out the resistor in and get a tune.

Or leave it out and get a tune. Either is fine.

 

[Dusten]

That fuel pressure is way to high. It should just 1:1 with boost.
You're going to need a tune for the pumps.
And only check idle with vacuum pulled. It should be 39-40, but 31 at idle means you're pulling 16" of vacuum and that perfect.

 

[Dusten]

It sounds fine but you always want to set for both no vacuum as the regulator adjustable based on vacuum/boost