05 wrx fuel issue

[sederholma]

Ive been fighting this issue for well over a month and ive gotten close, but it just got worse.

My fuel pump died (walbro 255) at the track. Blew my headgasket, rebuilt the motor, then went to turn it over and it cranked for a while then started up and started sputtering and running lean and etc.

After alot of diagnosing, i figured out it was my fuel pump.

Buy brand new walbro 450, install it, prime it, sounds great (the 255 started whining excessively so thats what gave that away) and everything was great! Throttle response, was fine, no backfires or anything.

Drop the car off the jack stands, start it up, go for a little drive and same stuff starts happening. AFRS start leaning out really bad. If im at 3.5 to 4grand, afrs are good. But once i shift into second and the RPMS drop to 2grand 2.5 grand, the afrs go lean and it starts sputtering really badly.

I limped it home and shut off. Let it chill for a few mins and then i went to start it again and fuel pumps whining like a stuck pig and it WOULD NOT start at all. It would just crank. Seemed like it was getting no fuel. Ok wtf?

Took it to a local subaru technician buddy of mine and he took the pump out and noticed the diaphram above the pump was knocked loose possibly causing a pressure leak. Ok, put it all back together. Still no start. But the pump isnt whining anymore so its good. Hes gonna do a pressure check thursday

But lets say hypothetically, if the pressure is fine, what might be going on? anyone else have this issue? injectors are fine. tune is fine. everything WAS running just fine before i took it on the road test right after i reinstalled a new pump. Im at a loss here

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[scooby24]

What the details on your fuel rail/FPR setup?

[subaru_gc8]

you know I was talking to a buddy that has a subaru shop and he ran across this subaru with a walbro 450 that had the same issue. he said it took him a long time but had something to do with the stock fpr and over releasing pressure on wot runs. thought that was kind wierd but maybe it has something to do with too much pressure and the stock fpr cant close.. dont know but there you go something do think about

[sederholma]

Originally Posted by scooby24

What the details on your fuel rail/FPR setup?

Stock fuel rail and FPR.

where is the FPR located? is it the little black circular thing in the engine bay?

[sederholma]

Originally Posted by subaru_gc8

you know I was talking to a buddy that has a subaru shop and he ran across this subaru with a walbro 450 that had the same issue. he said it took him a long time but had something to do with the stock fpr and over releasing pressure on wot runs. thought that was kind wierd but maybe it has something to do with too much pressure and the stock fpr cant close.. dont know but there you go something do think about

i was hoping it wasnt FPR related but i guess it may be. time for an upgrade. Thats the only other thing that could be causing this issue. thanks for the input