255lph pump installed runs like crap

Discussion in '94-95 5.0 - Specific' started by 95gt444, Aug 3, 2014.

  1. 95gt444

    95gt444 New Member

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    Planning on a vortech in the future so I upgraded fuel pump to bbk 255lph kit. Changed the filler neck grommet. Started up after priming pump idles great but has no power at low rpm or less then full throttle engine also sounds diffrent then it did before. With stock injectors do I need an adjustable regulator to lean it out?

    mods as follows


    Bbk 75mm tb
    bbk cai
    bbk 75mm maf
    trickflow street heat intake
    trickflow 75mm elbow
    emimissions gone
    a/c and p/s elimmated
    mac shorty headers mac offload h
    flowmaster catback
     
  2. BLWNBYU

    BLWNBYU Active Member

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    Pull the vacuum line off your regulator and see if there is any fuel in it
     
  3. 330CubeGt

    330CubeGt Well-Known Member

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    If you think about it all your mods listed are doing is leaning it out and the computer is taking care of fuel compensation.


    And going from a say 90lph to a 255 won't make the car run rich as long as nothing else has changed.

    -330CubeGt
     
  4. BLWNBYU

    BLWNBYU Active Member

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    Well, one would think that, but I just changed fuel systems and it dropped my AFR 3 points at idle, with NO other changes and I've spent a week trying to figure it out... I have numerous people stumped over on corral lol
     
  5. 95gt444

    95gt444 New Member

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    No fuel in the regulator vac line at all.
     
  6. OnyxCobra

    OnyxCobra Post Whore

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    Yeah I have to say just switching my fuel pump I didn't notice any difference in how my car ran. We have a fuel return so anything the engine doesn't use goes back to the tank.
     
  7. 95gt444

    95gt444 New Member

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    If the pump is pushing more volume possible regulator can't keep up?
     
  8. 330CubeGt

    330CubeGt Well-Known Member

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    7 Mustangs later thats all I have ever experienced. Even with dual 255s or a single 340

    Your pushing more volume to the same regulator and injectors, all its going to do for now is make sure you dont run out of fuel up top in the higher rpm's. But thats nothing you have to worry about right now.All the extra fuel its able to put out will make its way back to the tank through the return.
    Guys run more pump then you are on stock regs and dont have issues.Not saying its the beat but it's been done.

    -330CubeGt
     
  9. 95gt444

    95gt444 New Member

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    Car ran perfect with stock pump so not sure what the deal is. Tank is very low on fuel, maybe just not enough gas, lol. Pump and strainer are sitting in the baffle. Clamps and wires tight made sure hose didn't get cut when putting it in. All lines and electrical connectors clipped in place
     
  10. 330CubeGt

    330CubeGt Well-Known Member

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    So your trying to diagnose a problem and your very low on gas.

    So im thinking you might be the problem?

    -330CubeGt
     
  11. 95gt444

    95gt444 New Member

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    I didn't want too add more gas if I have to pull the pump back out make it heavier. I'll add some fuel. The engine runs great, but under load it hesitates,unless I give it lots of throttle, but accelerating slowly it hesitates.
     
  12. BLWNBYU

    BLWNBYU Active Member

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    Once you have emptied the tank it takes quite a bit of fuel to be able to make it back into the sump.....
     
  13. 95gt444

    95gt444 New Member

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    Yeah I didn't realize how low it was I put a gallon of 87 I had for my mower, it's raining so no test drive but seems to run and sound way better then before. Is a adjustable fpr and fuel psi guage worth it?
     
  14. BLWNBYU

    BLWNBYU Active Member

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    Adjustable regulator is not nescessary
     
  15. 95gt444

    95gt444 New Member

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    Drove car today much better, still feels sluggish a little. Psi at rail is 36psi vac line hooked up and 45 with vac line off regulator. Can i advance timing more now with more fuel psi currently at 10degrees but sct4 chip so not sure if the chip advances it?
     
  16. toyman

    toyman Active Member

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    No. By increasing the fuel pressure you gain nothing at idle and cruise except make the ECU adjust the injector pulse width to bring the AFR back into spec. This occurs because the ECU is programed based on a fuel load delivered at about 39 psi. At WOT the AFR sensors are turned off and the ECU uses a look-up table to deliver fuel when the TPS sensor is above about 75% open. What you can do is increase the base timing until the engine starts to ping. You might be able to see 14* advance with 87 octane but with the chip you don't want to physically make this change as it has probably been done in the SCT tune. The chip may have altered the oem timing settings but fuel load and timing are not related in the way you are thinking.
     
  17. 95gt444

    95gt444 New Member

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    Can too much fuel psi cost me power though with vac line off should be 39psi I'm am currently at 46psi
     
  18. RichV

    RichV Well-Known Member

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    It can. My tuning guy would not recommend over 42. Can you turn it down?
     
  19. 95gt444

    95gt444 New Member

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    Waiting on adjustable fpr
     
  20. Addermk2

    Addermk2 Well-Known Member

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    Probably kinked your return line.