need help with fuel pressure issues

[BOOST FREAK]

I need some help with a fuel pressure issue I am having with my car. the car has a whipple, single blade TB, headers etc. the first dyno attempt was with Focus pumps, and everything was fine on the part throttle tuning but when it came time for the WOT pulls the fuel pressure started fluctuating wildly. the high was 75psi and then would immediately drop to 5psi. it was so bad that we had to call it a day. the tuner suggested to go back to stockers and install a BAP. so I bought some pumps and a BAP from him and returned home. installed them and returned only to find the problem still there. we dropped the tank to look for loose hose. when he saw I deleted the PPRV he thought that was it, so he installed 2 PPRV's from some Focus pumps. put it back on the dyno and the fluctuation was gone. at this point I am happy, so I return home. I go to the track to try it out and I pop a fuse going from 2nd to 3rd. I check into it and it was a 20amp BAP, so I replace it with a 40amp and return to the track and the car just doesn't pull like it should on the back half 101mph 1/8 & 123mph 1/4. it did pick up a little mph in the 1/8, but my car with an un-ported eaton would go 124 in the 1/4....but I digress. so I data log the next pass and guess what, the fluctuation is back.

does anyone know what is causing this fluctuation?

and also what system should I do now? GT pumps, Fore hat, new line and dual stock or dual modified FPDM's......or go return style?

 

[04sleeper]

I don't think your fluctuation came from your PPRV delete. It may be a bad FPDM.


Running 2 Focus pumps on 1 stock FPDM may have messed it up.

I would try a new FPDM and try it with he BAP set @ 50.

Also, did you do a wiring upgrade when you installed the BAP?

I'm not really a big fan of the PPRV delete becausehey have been known to come apart on some people and the cheap plastic "Y" does not seem very trust worthy either.

A better set up would be the Fore Hat with twin GT pumps and dual FPDM's.

This is what I am going with for my upgrade.

FYI: I am currently running stock pumps with a BAP @ 50 and my FPDC is arouns 90% max with my Whipple @ 17 psi.

Edit: I was going to go with the return set up but I do not plan on running any more boost so I decided to go with the GT pumps instead.

I have some Fore Rails for sale if you are interested in going return. (See Sig)

 

[BOOST FREAK]

I changed the FPDM out with a new one and it made no change.

when you do the hat what lines are you going to use from the pumps to the hat? also are you going to use the single or dual outlet?

 

[04sleeper]

I changed the FPDM out with a new one and it made no change.

when you do the hat what lines are you going to use from the pumps to the hat? also are you going to use the single or dual outlet?

I am planning on running a -8 line to the rails and going with a single outlet from the hat.

I am also going with dual FPDM's VS a modified one.

 

[Juiced46]

I replied in your thread on Mod Fords as well

Had this same issue with my car a long time ago and thought it was the Focus pumps. Put in stock pumps and it still did it. Disconnected the BAP and still did it. It ended up being something in the tune with some corrupt SCT files. FP was all over the place @ WOT just like your car. No matter what was done to the tune the FP was fluctuating.