Running lean up top

[cuda6pak]

I have an 87 GN, TE44@16psi, mild port heads, art carr tranny and 3000 n/l, THDP, hooker exhaust, mease neck, Translator, 009 inj, hotwire walbro 340, turbotweak street chip, Accufab adjustable FPR.

I have the FP at 43psi and the WOT tables on the chip bumped up. It seems to run pretty good/rich down low 820-830 mV, but the higher up in the gear I go the leaner it gets, sometimes around 730mV or less.

What could be causing this? I've run boost leak tests and it BARELY leaks a bit at the FPR so it should be seeing the 1:1 with boost. I'm beginning to wonder if it maybe has a stock fuel pump in it or it's not hotwired?

 

[Hot Air]

What is the fuel pressure when the motor goes lean. You do have a fuel pressure gauge, don't you? If not, install a hood-mounted gauge (Jack Cotton can sell you a neat bracked for the gauge) or get one of the AutoMeter electric fuel pressure gauge and install it in a A-pillar pod.
Conrad

 

[cuda6pak]

What is the fuel pressure when the motor goes lean. You do have a fuel pressure gauge, don't you? If not, install a hood-mounted gauge (Jack Cotton can sell you a neat bracked for the gauge) or get one of the AutoMeter electric fuel pressure gauge and install it in a A-pillar pod.
Conrad

The FP gauge is under the hood. I need to run it up to the hood to check it under boost. But even so, at WOT at lower RPM and full boost it's rich...but up top in the RPM range at the same boost pressure it is much leaner.

 

[GNVYUS 1]

Post back your duty cycle up top when it starts to go lean.

You can always bump up the translator to add more injector up top if needed.

Sounds like a pump issue if 16psi is going that lean at 43 psi line off.

 

[cuda6pak]

Post back your duty cycle up top when it starts to go lean.

You can always bump up the translator to add more injector up top if needed.

Sounds like a pump issue if 16psi is going that lean at 43 psi line off.

I don't really have a way to look at the duty cycle as all I'm running is a Scanmaster.

 

[cuda6pak]

Is there anyway to check if the pump is dying? voltmeter?

It's supposed to be a walbro 340 hotwired, but I'm not sure how to check the hotwiring? I know I'd have to pull the walbro out to check what pump it is.