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  1. #1
    Nehemiah 5:19
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    Default What are symtoms of a bad fuel pressure regulator?

    I ask because I have some fuel in oil issues I want to cure. Also darkgrey exhaust smoke at WOT.

  2. #2
    Trolling like it's my job
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    Have you done a compression check? It sounds like fuel is getting past your rings, and/or you're getting oil in your cylinders. I don't think it has to do with your fuel pressure regulator, but I could be mistaken.
    1995 Maxima SE 5spd - lowered on 17" Altima SE wheels, headers, cat, cat-back, the necessities.

    2007 Honda Ruckus - WAY too many mods to list, but top speed is now 53+mph, as opposed to less than 40mph out of the box.

  3. #3
    Nehemiah 5:19
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    Could be. I am going thru a quart every 1k. Blackstone told me that my 10W40 is being thinned to 10W30 and there was iron traces? This was a few years ago.

  4. #4
    Trolling like it's my job
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    Do a compression check and post the numbers. I'm not sure what piston rings are made of, but iron would be my guess. I wouldn't be surprised if you had some metal flakes from your rings in your oil pan. And the gas in your oil would be caused by blow-by, which would also be a symptom of bad rings. Sorry for sounding like a broken record, but that's my best guess without actually being there.
    1995 Maxima SE 5spd - lowered on 17" Altima SE wheels, headers, cat, cat-back, the necessities.

    2007 Honda Ruckus - WAY too many mods to list, but top speed is now 53+mph, as opposed to less than 40mph out of the box.

  5. #5
    Resident Mathematician
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    Quote Originally Posted by Kickin_Wing View Post
    Do a compression check and post the numbers. I'm not sure what piston rings are made of, but iron would be my guess. I wouldn't be surprised if you had some metal flakes from your rings in your oil pan. And the gas in your oil would be caused by blow-by, which would also be a symptom of bad rings. Sorry for sounding like a broken record, but that's my best guess without actually being there.
    I second that, sounds very possible that's the case!
    B13 Quick Reference Package 95 M3 Perfection is simple, logical, and mathematical.

  6. #6
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    So what are the symptoms of a bad FPR? I'm getting random jumpiness, like a clogged fuel filter, but it only has two oil changes on it roughly 7k so it should still be good. Pump is less than 6 months old. could a bad battery terminal do this the ground is kinda old and busted. thanks for any help/advice

  7. #7
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    Well a bad FPR could cause you to run either rich or lean couldn't it? I'm not 100% on how they function but either way it would make your car run like crap. Misfires if too lean and bad mileage/low power if too rich.

    If you have bad grounds clean them up for sure, they can cause all sorts of random funk.
    B13 Quick Reference Package 95 M3 Perfection is simple, logical, and mathematical.

  8. #8
    Trolling like it's my job
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    Quote Originally Posted by Danja View Post
    Well a bad FPR could cause you to run either rich or lean couldn't it? I'm not 100% on how they function but either way it would make your car run like crap. Misfires if too lean and bad mileage/low power if too rich.

    If you have bad grounds clean them up for sure, they can cause all sorts of random funk.
    x2 on what he said

    Symptoms of a bad FPR can range from hard hot starts, an unexplained decrease in fuel mileage, rich exhaust (sulfrous smell), black tips, and even rich/lean fuel DTC's, which would most likely be caused by a rich/lean misfire.

    They run on vacuum, and a little diaphragm, kind of like an EGR. Manifold vacuum pulls on the diaphragm and allows a certain amount of fuel to pass. If the FPR is shot, you will most likely have fuel in the vacuum line, and I'm sure it's possible to have some in your intake manifold, as well, because the diaphragm ruptures.
    1995 Maxima SE 5spd - lowered on 17" Altima SE wheels, headers, cat, cat-back, the necessities.

    2007 Honda Ruckus - WAY too many mods to list, but top speed is now 53+mph, as opposed to less than 40mph out of the box.

  9. #9
    Aiming for 4 digit HP!
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    A bad FPR will make you run really rich. Black smoke coming out is indicative of running really rich, whereas blue smoke means you're burning oil. Best way to tell if your FPR has gone bad is to get a fuel pressure gauge, although it's not definitive - you could have low/high vacuum too, which would cause similar symptoms.

  10. #10
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    Thanks guys. I checked my injectors again to make sure none were leaking and one of them was. Thats what was causing the horrible gas mileage. Quarter tank in 25 miles. Fixed it and it's running smooth as eggs. How many miles does a FPR have in its life span: 175K? 200K? 50K?

  11. #11
    U.S. Army Soldier
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    Quote Originally Posted by The Goat View Post
    How many miles does a FPR have in its life span: 175K? 200K? 50K?

    It's one of those things that come with a YMMV factor, so there's no set amount of miles before it stops working correctly.
    "The greatest trick the devil ever pulled was convincing the world he didn't exist".

    -The Usual Suspects

 

 

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