Not sure if this is the right place to put but I hope you guys can help. I have a 03 mach1 with a 76mm on it and I'm having a problem with fuel pressure just dropping off. For instants my tuner made a pull yesterday and the fuel pressure stayed in the 45-50 psi range until about 5200 then drop to 14psi. He let off as soon as he saw it. What could be causing this issue to keep happening? Car has cobra tank and hat with 2 fgt pumps, jms bap, and 80's. My tuner said I would be best off converting to return style instead of trying to figure out what's wrong with the returnless. I dying to let this thing eat and have been hampered by this problem for weeks. Has anyone experienced anything similar. I'm running straight 110 race gas if that makes a difference. Thanks for any help or knowledge you guys can give me!
fuel pressure drop issue?
- Thread starter 4.6pimp
- Start date
What's the alternator voltage doing when it drops?
Damn good question... i will have to ask my tuner and see what he says. I'm new to the returnless systems and trying to learn as I go.
Check your fuel filter.
Replaced it last week when I did the hoses and pprv delete
I would double check the connections on the PPRV Delete. The are notorious for leaking/kinking. That's why most go with a new billet fuel hat.
With 2 GT pumps and a BAP, you should easily have enough fuel on 110.
With 2 GT pumps and a BAP, you should easily have enough fuel on 110.
Hmmm, you shouldn't be maxing out the 80's so you should be good there. What was the injector duty cycle and did you do anything with your FPDM? Hopefully its something simple like voltage/alternator.
As far as I know it is the stock single fpdm.. maybe it is getting over heated and shutting down. Will find out more this weekend. Is there anyway to check that while not on the dyno?
Looks like I have sometime to mess with the mach and I'm thinking about going ahead and doing the wire upgrade from lethal for fpdm and bap. Like I said I'm new to this so how can I go about checking voltage to the fpdm? Should it be 12 volts at all time? Anyway to check voltage to pumps with out being on the dyno? Will a after market hat and dual fpdm help me out also? Thanks for any help and words of wisdom...
The 2v/4v fpdm will go into thermal shutdown at around 20amps, ford gt pumps draw around 8-10amps a piece, with a bap that amperage is going to go up. My money is on fpdm shutting down. What is fuel pump duty cycle when the pressure drops? This will shed some light as well.
I would upgrade to 10awg wiring everywhere and add a second fpdm if you don't have two. Make sure to feed the bap right off the battery or fuse panel via a relay triggered by the inertia wire. Then split the output of the bap to the input of each fpdm. Again all wiring between bap and fpdms should be at least 10 gauge. A properly setup dual ford gt pump, dual fpdm with a bap config will support 700-800rwhp.
Or you could go return.
I would upgrade to 10awg wiring everywhere and add a second fpdm if you don't have two. Make sure to feed the bap right off the battery or fuse panel via a relay triggered by the inertia wire. Then split the output of the bap to the input of each fpdm. Again all wiring between bap and fpdms should be at least 10 gauge. A properly setup dual ford gt pump, dual fpdm with a bap config will support 700-800rwhp.
Or you could go return.
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Jeremy H. I thought the same thing so I got another fpdm and pig tail. Ran 8g from battery and 10 every where else. Going to run 10g to pumps tomorrow and fire it up. Will have to wait a week before I can get back to dyno. Thanks for the info
:thumbsup:
I'm running twin GT pumps with a stock FPDM and wire upgrade. Worked great up to about 600hp. Now I need bigger pumps. But my stock FPDM has never gone into thermal shut down.
I ran the same setup for awhile no problems, I had upgraded wiring to the fpdm and from the fpdm to the hat. Made 655rwhp on that setup with a little room on a single turbo.
I vote going to a return setup and calling it a day. You can sell off all your current fuel upgrades to recoup some funds.
This was my last ditch effort on the returnless system. I have about 150 bucks in this wire and extra fpdm upgrade. If it works I'll run it until I save the money for the return style.
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