Just installed WB into a friends FD.. she's stock seq twins running Apexi PowerFC. Mods are K&N intake, downpipe and large bore catback.. stock cat is in place. We did a few 3rd / 4rth gear runs and I notice she's leaning out under high load / high rpms.. she's at 100% duty cycle at 6000 RPM's and approx 10 PSI. At this stage she's starting to lean out to high 11's all the way to 13's in higher RPM's!

So far we only had a chance to change the fuel filter, note the old one seemed like new. Next step might be to swap out the pump and see if it's pump / fuel pressure related (don't have a fuel pressure gauge).

Anybody experience issue like this with stock FD? Suggestions from people with similar experience?

 

pump is failing.

 

Is this a common problem? Car has approx 50k miles..

Gonna swap the pump out of my other FD and see if it makes a difference, then get a new pump for the guy..

 

I've also heard of crap coming loose in the gas tank that can block off the pump inlet some and starve flow. While you are back there it's a good opportunity to improve the ground side of the pump power supply circuit to give the pump a bit more voltage, simply ground it to a solid chassis ground location near the pump. My guess is it will be way rich when you fix the fuel supply issue if the injectors are maxed out at 6000 rpm.

 

If you really want to know, you need a FP guage. Most likely pressure cannot keep up with boost at high RPM. This is generally due to wires that are too small going to the pump(stock wires). Otherwise time for an aftermarket FPR. Carl