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Thread: Pre 96 fuel pressure regulator diy?

  1. #1
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    Pre 96 fuel pressure regulator diy?

    I can see the damn thing behind the engine block by the fuel rail but i cant figure out how to get to it. All i really need to do is check the vacum line to see if it smells like gas. Any suggestions? The only diy i found from autozone.com says to remove dme and dme wiring cover.

    95 325i help plz

  2. #2
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    Remove the plastic rail cover.
    Remove the hoses from the fuel rail, there is one feed in the front and a return in the back.
    Unplug wiring harness from injectors.
    Remove 2 bolts holding fuel rail on.
    Pull rail and injectors out, disconnect vac line.

    Seeing whether the vac line smells like gas really isn't a good way to diagnose a FPR. Either just replace it since it is cheap, or get a fuel pressure gauge and do some actual diagnostic work.

  3. #3
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    Where should i tee into the fuel line? Id rather not do it by the fuel filter because i think its the fpr. What do i need to get like an adapter or something? I have the pressure gauges

  4. #4
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    bump

  5. #5
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    Tap into the feed line at the front of the rail. It's 5/16".

  6. #6
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    ok so i just buy the tee and thats it? Do i need extra hose

  7. #7
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    Quote Originally Posted by Million View Post
    I can see the damn thing behind the engine block by the fuel rail but i cant figure out how to get to it. All i really need to do is check the vacum line to see if it smells like gas. Any suggestions? The only diy i found from autozone.com says to remove dme and dme wiring cover.95 325i help plz
    , Just pull out the hose with tweezers or long nose pliers. Reinsert with the tweezers the same way, just put a little oil on it to make it easier. Don't pull off the whole rail just to get at the regulator.
    Quote Originally Posted by rajicase View Post
    Remove the plastic rail cover.Remove the hoses from the fuel rail, there is one feed in the front and a return in the back.Unplug wiring harness from injectors.Remove 2 bolts holding fuel rail on.Pull rail and injectors out, disconnect vac line.Seeing whether the vac line smells like gas really isn't a good way to diagnose a FPR. Either just replace it since it is cheap, or get a fuel pressure gauge and do some actual diagnostic work.
    No, smelling that vacuum hose is an excellent way to tell if your regulator is damaged. And all the work you've described to change it you'll avoid if its not damaged. The key is how and where you pull it off.

    Firstly, only pull it off after you've run the engine for 10 minutes, or come back from a drive. Pull it off immediately. Secondly, what do you want to check? The regulator? Then immediately pull it off at the manifold end and leave it dangling for a few hours for any seepage to happen. Then smell it.

    Do you want to check if your fuel injectors are leaking? Then immediately pull the hose off at the regulator end and leave it dangling for a few hours for seepage if any to accumulate. Then smell it.

    If you leave it for a few hours and then pull and smell, you won't know if any gasoline smell is coming from a damaged regulator diaphragm or leaking injectors.

    Regulators hardly ever go even after 20 years. Wish the rest of the car was that way. So unless you have diagnosed a problem with it, or you are removing the rail for other reasons and its just convenient to change one out to new and you feel like it, don't muck with it. That's my advice.

    DRJ
    Last edited by DrJBM; 03-20-2017 at 12:12 AM.

  8. #8
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    ^Please ignore this guy...
    If you see obvious fuel leaking from the vac hose, then obviously the regulator is bad. But just because you don't see leakage from the hose, doesn't mean the regulator is good. You sound like a shade tree mechanic that diagnoses head gaskets by sniffing the exhaust...

    - - - Updated - - -

    Quote Originally Posted by Million View Post
    ok so i just buy the tee and thats it? Do i need extra hose
    You might.

    See what your gauge kit comes with. You may need some extra hose and clamps.
    Last edited by rajicase; 03-21-2017 at 04:13 PM.

  9. #9
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    Rajicase, are you also calling Shogun a shade tree mechanic? Because here he is recommending pulling the vacuum hose to check on the regulator too:

    https://www.bimmerforums.com/forum/showthread.php?2329612-Fuel-Delivery-Problems-SOLVED&p=29602218#post29602218

    Of course the best way to check everything is to dismantle everything and put it on factory gauges and oscilloscopes. But that's not what we're doing here. Simple methods that work for 95% of the time for problems are enough. Just because you once had a problem that needed the 5% method doesn't mean you recommend that as a first approach to the problem. I mean, unless you want to buy the gauge and do the work for the OP for free.You certainly don't knock someone recommending the 95% effective method.

  10. #10
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    The sniff test is fine for detecting a defective FPR due to diaphragm failure,
    but it does not confirm that the regulator is good, as Rajicase correctly stated.
    Only a test at the fuel rail with a FPG, can confirm proper fuel pressure is being supplied.
    So technically everyone is correct, dependent on what is being tested and confirmed.

  11. #11
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    Quote Originally Posted by ilikemycar View Post
    Rajicase, are you also calling Shogun a shade tree mechanic? Because here he is recommending pulling the vacuum hose to check on the regulator too:

    https://www.bimmerforums.com/forum/showthread.php?2329612-Fuel-Delivery-Problems-SOLVED&p=29602218#post29602218

    Of course the best way to check everything is to dismantle everything and put it on factory gauges and oscilloscopes. But that's not what we're doing here. Simple methods that work for 95% of the time for problems are enough. Just because you once had a problem that needed the 5% method doesn't mean you recommend that as a first approach to the problem. I mean, unless you want to buy the gauge and do the work for the OP for free.You certainly don't knock someone recommending the 95% effective method.
    YES I am saying that smelling a vacuum line for fuel to determine whether or not your FPR is good is absolutely, without a doubt, shade tree mechanic type work. If you don't like it, too bad. There is more than one failure mode to a FPR, and smelling the vacuum line only rules out ONE.

    Think about it like this, if you took your car to a mechanic and paid them $100/hr to diagnose a FPR (or to determine whether your FPR was bad) would you be satisfied with him calling you up and stating; "Your FPR is fine, I pulled the vac line off and sniffed it." I would hope not, because he has not done sufficient testing to make such a statement.

    Just because you are satisfied with your shade tree, lazy means of diagnostic work doesn't make it less shade tree/lazy.

    Try and wrap your head around this scenario; A FPR is not functioning properly. Diaphragm is intact. Your shade tree tactics would conclude that the FPR is GOOD. And then send yourself/whoever takes your advice on a wild goose chase, replacing everything under the hood EXCEPT the FPR. Good job, your laziness saved you 30 minutes of actual diagnostic work up front and cost you $$$$$ and hours in the end.
    Last edited by rajicase; 03-26-2017 at 05:21 PM.

  12. #12
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    Quote Originally Posted by MIKYZZ4 View Post
    The sniff test is fine for detecting a defective FPR due to diaphragm failure,
    but it does not confirm that the regulator is good, as Rajicase correctly stated.
    Only a test at the fuel rail with a FPG, can confirm proper fuel pressure is being supplied.
    So technically everyone is correct, dependent on what is being tested and confirmed.
    Which is exactly what you need to do when trying to track down a fueling issue. Unless you definitively conclude the FPR is good before moving on to the next idea, you are only screwing yourself over.

    If the diaphragm is shot and you see/smell fuel from the vac line, GREAT. Your FPR is bad, replace it. But as stated, a FPR can fail in more than one way and just because it isn't leaking doesn't mean it is good.

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