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infrequent drop in FRP

1K views 2 replies 2 participants last post by  ericinboca 
#1 ·
I have a 2009 F250 with 110K miles, and about 2900 hours, deleted but with no HP tune, just the delete.

Infrequently, I get a momentary loss of FRP - in a fraction of a second, it drops and recovers. It happens so fast, it is hard to turn your eyes to the digital monitor to see the FRP change.

It only does it when I am working the throttle with my foot - never when on cruise control. And it has only done it maybe a dozen times in the last 15K miles. It has done it while towing, and it has done it while empty.

Some history....

It has a HPFP that is less than a year old - replaced because the volume control valve failed. Cab off job.

Both fuel filters are changed every 5K miles when I do oil and filter.

It had water contamination in the HFCM, along with some sludge - but I do not believe it went past the HFCM, at least there has been no evidence of anything in the filter on top of the engine or in the bowl. Consistently the filter on top looks new after 5K, while the one on the bottom has occasionally caught stuff. Never any metal in top bowl - no rust, nothing.

When I found water in the HFCM, I removed, cleaned, rebuilt and also eventually replaced the lift pump with a new Racor, thinking maybe it had been damaged internal by water.

Yet I still have this infrequent issue.

There are no codes, and otherwise you could balance a nickel on its edge on the motor - it starts instantly and pulls like a freight train.

Anybody have any ideas?
I'm wondering about why it only does it when off cruise control. Pedal position sensor?
 
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#2 ·
I'd probably want to record some data with the problem occurring. Frp, frp desired, frp voltage, vcv, pcv.
I'd probably start there. With issues that occur so briefly, it's best to record in graph form.
App is a pretty heavily guarded circuit. A fault would likely throw a DTC.
 
#3 ·
Update -
I have also removed and cleaned the upper fuel bowl, and put in a new fuel rail pressure sensor (just cause the whole thing is driving me crazy.)

But more importantly, Autoenginuity arrived yesterday. Playing around with it, it shows great power balance, and found no codes other than dash light dimming switch (which I knew).

The truck goes to WVA in a couple of weeks. I will monitor with AE and try to capture data if it does its fuel pressure drop thing.
 
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