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Erratic fuel pressure and boost gauge not working

Posted by mattp_65, Nov 16, 2013

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  1. mattp_65

    mattp_65 Proven Member

    243
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    Joined Aug 16, 2004
    Lake Stevens, Washington
    https://www.youtube.com/watch?v=1QbDIdKV0cI

    Fuel pressure is erratic and boost gauge is running at 7psi even though it's at idle. MAP shows it is in vacuum. But I installed a new 450lph walbro pump with added an fittings on hangar with new -6 lines. Cleaned out aftermarket filter ss mesh. Is my aeromotive fuel pressure regulator going bad? It was fine with the 255 pump. I also did the siphon mod and opened it up a little. I can't regulate the fuel pressure at all. The more I loosen the bolt it will come out if the regulator.
    The only thing I have not checked is the regulator itself. Is my pump not working properly? Please help I need help.
    I don't know if my fuel pressure and regulator are related but both were working fine before installing the new pump.
     

    Street Build 608  1

    1978 Chevy LUV
    automatic · 4G63t Swapped

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    1995 Eagle Talon TSi AWD
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  2. Tyeler18

    Tyeler18 Proven Member

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    Casa Grande, Arizona
    Is your boost gauge tied into the line to the FPR? If so i'd assume your vacuum line is torn somewhere.
     

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  3. mattp_65

    mattp_65 Proven Member

    243
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    Lake Stevens, Washington
    Yes they are but the lines are very short and all the lines look good to me. Could be that my gauge is going bad? It's an electronic greddy boost gauge. 60mm
     

    Street Build 608  1

    1978 Chevy LUV
    automatic · 4G63t Swapped

    1K  1

    1995 Eagle Talon TSi AWD
    11.98 @ 125 · 2G DSM

    680  0

    1995 Eagle Talon TSi AWD
    12.04 @ 121.000 · 2G DSM
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  4. 97_4g63t

    97_4g63t Supporting VIP

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    Joined Jun 6, 2010
    carlsbad, New Mexico
    You try just turning your fuel pump on with link and checking the pressure? Take the vacuum line off too to make sure it aint blowing by.
     

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  5. mattp_65

    mattp_65 Proven Member

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    Joined Aug 16, 2004
    Lake Stevens, Washington
    I have and it is normal pressure. Only erratic with car on. This is so confusing LOL
     

    Street Build 608  1

    1978 Chevy LUV
    automatic · 4G63t Swapped

    1K  1

    1995 Eagle Talon TSi AWD
    11.98 @ 125 · 2G DSM

    680  0

    1995 Eagle Talon TSi AWD
    12.04 @ 121.000 · 2G DSM
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  6. Tyeler18

    Tyeler18 Proven Member

    2,065
    76
    Joined Dec 16, 2008
    Casa Grande, Arizona
    Run a new vacuum line for the FPR and the boost gauge. It's cheap, and probably your problem. If you pull the vacuum line off the FPR does gas come out of it?
     

    Drag Race Build 611  1

    1991 Eagle Talon TSi AWD
    awd · automatic · 1G DSM

    Road Race Build 657  0

    1990 Eagle Talon TSi AWD
    manual · 1G DSM

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    1998 Mitsubishi Eclipse GSX
    manual · 2G DSM

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    1991 Mitsubishi Galant VR-4
    manual · Galant VR-4
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  7. mattp_65

    mattp_65 Proven Member

    243
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    Joined Aug 16, 2004
    Lake Stevens, Washington
    No gas comes out of the line.
     

    Street Build 608  1

    1978 Chevy LUV
    automatic · 4G63t Swapped

    1K  1

    1995 Eagle Talon TSi AWD
    11.98 @ 125 · 2G DSM

    680  0

    1995 Eagle Talon TSi AWD
    12.04 @ 121.000 · 2G DSM
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  8. Tyeler18

    Tyeler18 Proven Member

    2,065
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    Casa Grande, Arizona
    Then you're pretty much limited to a torn line.
     

    Drag Race Build 611  1

    1991 Eagle Talon TSi AWD
    awd · automatic · 1G DSM

    Road Race Build 657  0

    1990 Eagle Talon TSi AWD
    manual · 1G DSM

    Autocross Build 862  0

    1998 Mitsubishi Eclipse GSX
    manual · 2G DSM

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    1991 Mitsubishi Galant VR-4
    manual · Galant VR-4
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  9. miguelmcv

    miguelmcv Proven Member

    2,051
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    Joined May 3, 2009
    Fresno, California
    What exactly happens when you try to adjust the fpr?, the the fuel keeps the same pressure?, those the pressure goes up or down?.

    Give us more details on what it does.

    I have had a bad O ring pump and the fpr doesn't regulate, it stays on the same pressure no matter what I do, obviously, this is with the car on,. I replaced the fpr with a new one and the problem still there, that's when I realized the problem was somewhere else.

    Tell us more details on what's going on when adjusting the fpr.
     

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  10. mattp_65

    mattp_65 Proven Member

    243
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    Joined Aug 16, 2004
    Lake Stevens, Washington
    Adjusting the bolt to tighten raises the pressure a little and loosening does nothing.
     

    Street Build 608  1

    1978 Chevy LUV
    automatic · 4G63t Swapped

    1K  1

    1995 Eagle Talon TSi AWD
    11.98 @ 125 · 2G DSM

    680  0

    1995 Eagle Talon TSi AWD
    12.04 @ 121.000 · 2G DSM
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  11. mattp_65

    mattp_65 Proven Member

    243
    39
    Joined Aug 16, 2004
    Lake Stevens, Washington
    Ok so I put my old 255lph pump back in and now I can adjust the regulator. What gives? Is my new 450 not working properly or did I not install it right? Need help again.
     

    Street Build 608  1

    1978 Chevy LUV
    automatic · 4G63t Swapped

    1K  1

    1995 Eagle Talon TSi AWD
    11.98 @ 125 · 2G DSM

    680  0

    1995 Eagle Talon TSi AWD
    12.04 @ 121.000 · 2G DSM
    Loading...

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