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Thread: How to tell if i have a bad fuel pressure regulator

  1. #1
    Senior Member Luminatorz34's Avatar
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    How to tell if i have a bad fuel pressure regulator

    I recently just bought a nice 95 dodge ram with the 360 in it...it runs/drives great. but has a problem when trying to start it..previous owner told me its a bad fuel pressure regulator. basically when you try to start it, it does not start. you can crank as long as you want it will not start...but if u crank, let off the key, then hit it a 2nd time, itll start right up....ive never had fuel regulator issues before, so i dont know exactly what it should, or should not be doing....the previous owner recommended turning the key on a few times to cycle the fuel pump, which this does help a litttle bit, but not a very legit way of trying to start it....like i said, i dont know the fuel system enough to know what could be the culprit for a bad pressure regulator, or maybe even something else??? from what ive searched and found, this regulator is directly on the pump, so that inolves dropping the tank to get to it, to fix this. so i want to make sure it is the regulator to save myself a bunch of headaches involved in dropping the tank.
    2007 Pontiac Grand Prix GXP
    2006 Dodge Ram 1500
    1999 Camaro Z28

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    Owner AutoMods's Avatar
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    Re: How to tell if i have a bad fuel pressure regulator

    I would think if the regulator was bad it would run bad all the time. Could be the check valve on the pump so the lines loose pressure right away when the car is not running (startup) or the pump not priming the lines effectively. maybe you could easily hot wire the fuel pump so its always running and see if the truck fires right up when its wired like that.
    9.875@150mph
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    Senior Member Luminatorz34's Avatar
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    Re: How to tell if i have a bad fuel pressure regulator

    well something else i forgot to mention is that, after i get it started, it kinda runs like shit for a lil bit, then slowly comes out of it....and when i shut the truck off, and goto start it right back up, it will start up like it should...but if i wait like 10-15 minutes it does the whole not wanting to start thing again
    2007 Pontiac Grand Prix GXP
    2006 Dodge Ram 1500
    1999 Camaro Z28

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    Senior Member s13kid's Avatar
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    Re: How to tell if i have a bad fuel pressure regulator

    They make fuel pressure testers. You can rent them at any parts store.

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    Admin Drifte's Avatar
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    Re: How to tell if i have a bad fuel pressure regulator

    Do the basic maintenance and see if it changes at all.


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    Moderator 69gt4speed's Avatar
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    Re: How to tell if i have a bad fuel pressure regulator

    On a 03 cobra w upgraded fuel crap, some pumps, they did not include a check valve and all the fuel would drain back to the tank and like take a extra 30 sec to refuel. So those guys would turn the key on but not in start pos till 30 sec. Can't tell you if that is your problem but might try it. 03 cobras have a frps (fuel rail pressure sensor) through which it monitors fuel pressure. Till fp hits 39 psi it tells pump to stay pumping till it gets that.

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    Senior Member Luminatorz34's Avatar
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    Re: How to tell if i have a bad fuel pressure regulator

    if i get ahold of a fuel pressure tester, what exactly would i be looking for? pressure with the key on, truck off? truck running? what?
    2007 Pontiac Grand Prix GXP
    2006 Dodge Ram 1500
    1999 Camaro Z28

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    Re: How to tell if i have a bad fuel pressure regulator

    It seems you are looking for someone to work on it for you.

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    Senior Member Luminatorz34's Avatar
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    Re: How to tell if i have a bad fuel pressure regulator

    uh, no i dont want anyone to work on it for me..i know how to do my own work, just never had a fuel issue like this pop up for me...i just want to know what im testing for...like if there is a certain amount of time that i should expect fuel pressure to fall off, or what exactly i should expect when testing the pressure
    2007 Pontiac Grand Prix GXP
    2006 Dodge Ram 1500
    1999 Camaro Z28

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    Owner AutoMods's Avatar
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    Re: How to tell if i have a bad fuel pressure regulator

    Well ideally the pressure goes up to where it should be during priming, you'll have to look up where base fuel pressure should be on that vehicle, most vehicles 38psi-60psi range. As long as it primes up to that pressure while cranking it should fire up. Otherwise your problem is elsewhere. Pay attention to if your fuel pressure regulator is vacuum referenced as you may need to test with the vacuum disconnected from the fpr.

    Its nice if you vehicle holds full fuel pressure for a while when it is off but if it doesn't thats not a big deal, regulators often bleed that fuel pressure off or the pump check valve lets that pressure go back to the tank when they get old.

    And then of course during idle and cruise your fuel pressure should be at full pressure.
    9.875@150mph
    2012 Iowa Manual Shootout Champion, on low boost setting. -Flying Ryan
    "The bitterness of poor quality remains long after the sweetness of low price is forgotten." - Ben Franklin

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