Thanks for the reply Rotary Knight...

I presume me changing to the RP fuel pump will have a negative effect on HP?
More rich less HP... rather than lean and risk my engine.

Will it cause a rich idle though...? Rotary Performance says it will work fine with Upgraded ECU's... anyone Know?
jc.

 

I don't have problems running rich at idle with the A'PEXi pump, so I doubt any of these pumps will give you a rich idle problem as long as you keep the stock dual-speed (dual voltage) fuel pump wiring.

If you get a better pump and it makes you run rich under boost, your old pump was inadequate and you needed an upgrade anyway to be able to tune the car properly. If your old pump was inadequate, you could run lean when the radiator fans come on or you have the stereo pumped up (electrical load). The fuel pressure regulator is there to provide consistent fuel pressure that is independent of electrical load. If you run lean after adding a pump, your old pump was not able to maintain the regulator pressure which is a very bad situation. Don't worry about running rich with a big pump. If you do and your engine is still running, consider yourself lucky and go get the car dyno tuned with a wideband (often the cheapeast way to get more power and reliability).

-Max

 

It was my fuel filter not pump that now causes me to run rich. Filter was prob a bit clogged when i was on the dyno.

 

I added a RP this spring. I think it might be running lean at WOT high boost and in 4th gear.

I have a small n-tech battery and underdrive pulleys from Pettit and Greddy.

Can this be causing my lean condition? Getting a little knock. What can I do to fix? I'm sure my Hurley 3mm can take so much...
help jc.

 

Unless you're in the neighborhood of 500 rwhp, your rp shouldn't be losing fuel pressure causing you to have a lean condition...I've seen them dyno tested past 420rwhp with NO problems.