robert_barnes181

99 mustang cobra with procharger fuel pressure is fine until car runs for 30 minutes fuel pressure spikes out and stays there 65 pounds until car sets for hour or so then it returns to 32 pounds

Blackvenom01

you need to talk to your tuner and have him data log that dude...thats pretty high for idle thats just dumpin fuel in there

robert_barnes181

yes car runs like crap when fuel pressure gets that high at low rpm's i have talked to procharger and ford no one seems to have a clue. if i am not mistaking there is three main componets to fuel system please correct me if i am wrong.
1 fuel pump witch has internal regulater ( pump from procharger came with kit approx 5 years old)
2 fpcm located in trunk
3 fuel pressure sender loctaed on fuel rail
was thinking at replacing fuel pump with svt focus pump but hate to just start changing parts would like to know what problem is. i have snap on scanner with logging i have watched it do this dozens of times car will run for approx 20 minutes then fuel pressure just starts climbing to 65 pounds over a 10 min approx time frame
any ideas would be great help even at this point thank you

Blackvenom01

so who tuned your car...if its just a mail in tune that came with the procharger then your tune is crap cause every car is diff...what im sayin it take it to a dyno tuner he can see whats going on while getttin a great tune for it...thats what i would do if it was me

robert_barnes181

yea called a place in tulsa today have to take it in next week but he said fuel pressure problem needs to b fixed before he tunes

robert_barnes181

also forgot to say that after car heats up if u shut car off turn key on fuel pressure returns to 32 pounds but as soon as u start motor right back to 60 so motor has to b running

Blackvenom01

i dont like that he said that haha my fuel pressure would drop to nothing when i shifted gears under full throttle and told me tuner an we data logged it and figured out it was a tuning issue with the fuel pump and boost a pump...i wish i had more to help dude but thats def wierd...i mean it has to be something with the pump cause the pump is what gives it pressure but why is the pump doing that is the next question...i wonder if something go unplugged somewhere such as a 02 sensor and your car isnt registering the oxygen and when it does that it just dumps fuel!!

robert_barnes181

the reason he said that was car has been fine for past two years under present tune just started doing this couple of months ago so every one seems to think its mechanical

robert_barnes181

Ok replaced fuel pump put n gt40 pump and fuel rail pressure sensor no fix pulled chip started car pressure still at 60 pounds so not n tune can any one help I'm lost don't know were else to look

Blackvenom01

hmm i wonder if your computer is tellin it to richen up...do you have a return style fuel system or is it basically stock minus rails and pump...have you checked your MAF see if thats dirty....