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Thread: fuel pressure problem

  1. #1
    Junior SCH Member
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    fuel pressure problem

    i just got my fuel pressure guage installed and noticed that when the car goes into boost the fuel pressure will rise to about 70 or 80 then it bounces around like crazy from 40 to 80 and its all over the place need suggestions on what could be cause this also do you think it would be ok to go with no fmu and a adjustable fuel pressure regulator mods are full exhaust, trick flow intake, 70mm mass air , 30# injectors walbro 255 hp pump novi 1k will be putting the f150 pulley back on tuesday.?

  2. #2
    Senior SCH Member Chuck's Avatar
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    Are you running the stock fuel pump now?

    I think if you are that is your problem, it just cant meet the demand.
    1993 notch, 357W forged pistons 9.2-1 comp,Vortech S-trim 3" / 8" pullies, AFR 185 heads, Trick Flow R intake, Anderson B451 cam, PMAS 80mm, 06 PMS, 60# injectors, 3.55 gears and PA SC C4, Dual Walbro fuel system. Best ET 10.35 @ 135mph

  3. #3
    SCH Moderator 5150 LX's Avatar
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    You can dump the FMU with your mods, the 255 & the 30's will be enough.
    Quote Originally Posted by Kato Engineering
    you just like the metric system because when you talk about your organs length, a three digit number seems to you longer than a one digit number....
    Dart Block 331 and No Power Adder, currently in pieces...... :weird:

    Used to run 6.90 @ 100.4 mph in the 1/8th

  4. #4
    Junior SCH Member
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    ok i am gonna go ahead and get rid of the fmu then. but i would still like to know what could be cause my fuel pressure to bounce all around it is not a stock pump it is a high pressure 255.

  5. #5
    SCH Member
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    What is the FMU calibrated for. I may be interested in buying it. let me know if you want to get rid of it.
    93 5.0 LX Silver Coupe w/ chorme pony's on nitto drag radials. Mods: NOVI 1000, 8"crank, Performer Inake, 70mm TB, 75mm PRO-M, 24lb injectors, 255lph fuel pump, adj. fuel pressure regulator, eql headers, off road H-pipe, flowmasters, 373 gear, electric Fan, ect. Stock Long Block.
    http://www.partyclemson.com/photo_photo.aspx?user=25599&photo=37926

  6. #6
    Junior SCH Member
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    its calibrated for 30s i think i still have the original 19 calibration also i will let you know i have to see how it runs first without it then i will post back.

  7. #7
    SCH Member
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    send me an email at tram1062@bellsouth.net if you want to sell the FMU that is calibrated for the 30s. I have 24lb injectors and i am not running an FMU right now and i am running a little lean but if i use the FMU i have (the original 19 calibration) i run so rich its crazy.
    93 5.0 LX Silver Coupe w/ chorme pony's on nitto drag radials. Mods: NOVI 1000, 8"crank, Performer Inake, 70mm TB, 75mm PRO-M, 24lb injectors, 255lph fuel pump, adj. fuel pressure regulator, eql headers, off road H-pipe, flowmasters, 373 gear, electric Fan, ect. Stock Long Block.
    http://www.partyclemson.com/photo_photo.aspx?user=25599&photo=37926

  8. #8
    Junior SCH Member
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    ok but what about my fuel pressure probloem anyone have any ideas what is causeing this ?

  9. #9
    Senior SCH Member RydeOn's Avatar
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    Huntington Beach, CA
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    try disconnecting the FMU first like they said. possibly it is hooked up wrong or is defective
    93 Cobra - NOVI 1000 new style, Walbro GSS340, 130AMP alt, Griffin radiator, Mercury Sable fan + Delta Controller, Bassani offroad X, Magnaflow with 3" tailpipes, Tokico Illuminas, FRPP driveshaft, 3.55s, Nitto 555s (extremes up front and drags out back), Ultralite boost and EFP gauges

    91 bigass Bronco 4X4, to crush ricers with

  10. #10
    Junior SCH Member
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    something else i have come to find when i shut the car off fuel pressure is still at like 40 or so then i will come back later and it will be lower is this a sign of a leak and how would i find a leak if there was one? Or is it supposed to do this i dont think it is

  11. #11
    SCH Member
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    i belive it is suppose to do that b/c mine does the same
    93 5.0 LX Silver Coupe w/ chorme pony's on nitto drag radials. Mods: NOVI 1000, 8"crank, Performer Inake, 70mm TB, 75mm PRO-M, 24lb injectors, 255lph fuel pump, adj. fuel pressure regulator, eql headers, off road H-pipe, flowmasters, 373 gear, electric Fan, ect. Stock Long Block.
    http://www.partyclemson.com/photo_photo.aspx?user=25599&photo=37926

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