knappbunch

I Have a 402 with fast 92/92 and tfs cnc235 heads, have walbro 255 pump with racetronics wiring harness, have stock rails 42 lbs bosch ford injectors. Problem is at the top end we are running out of pressure and fuel. what could it be is the pump bad or could there be a problem with the line? It has new fuel filter and the pump is less than a year old what can be some of the possibilities? See Sig for Dyno Sheet.

Lonnies Performance

iTrader: (16)

You are reaching the limits of a single pump.

It is common to see a slight pressure drop due to the rear mount regulator, but you should only lose a few pounds.

Feel free to cantact me if you are looking to upgrade your system.

koolaid_kid

iTrader: (21)

I agree. You should have a BAP option on your harness, but I have read up on them and they are a patch only, not a solution. And don't believe what KB says; his examples are for a Ford which runs at 13v. The BAP boost it to about 17v.
Your harness already runs at 14.4v or so, so the increase will not be as great. And they are quite expensive for what they do, which is merely boost voltage at high useage times.