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Thread: Bosch 772 manual fuel pressure regulator replacement

  1. #1
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    Bosch 772 manual fuel pressure regulator replacement

    HI all,

    I am looking for a replacement for the Bosch 772 manual fuel pressure regulator. I could go the FWD performance route of a new regulator and fuel rail but I am wondering if there is a replacement that will fit the current (OEM?) fuel rail.



    Thanks,
    Ben
    Last edited by dr_amx; 04-02-2019 at 09:48 AM.

  2. #2
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    Re: Bosch 772 manual fuel pressure regulator replacement

    Hi Ben,
    I'm close to you in Bloomington. What is your vehicle or application? 772 Bosch regulator? Is that the part # on the regulator? Most people when using an adjustable fuel pressure regulator on a stock fuel rail, use the Accufab regulator. It is pretty much a bolt in, but you need to shim it with a couple washers or you'll booger up the bung on the fuel rail. You can also file the points off the hex bolt, and not use the washers (that's what I do). 2nd picture is what happens when you don't use the washers, and aren't paying attention! It's original application is for a Buick. (GN/T-type/TA/Typoon) Part # is BREG

    The fitting coming out of the regulator NEEDS an o-ring to seal. The 88-89 fuel rails have a return fitting that bolts into the Accufab. If you have an earlier style you will need to come up with a proper return fitting. DON"T use a brass hose nipple pipe thread with Teflon tape wrapped around it. Fire waiting to happen! See pics for correct style fitting. PM me if you need anymore info.
    Todd
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  3. #3
    turbo addict Turbo Mopar Contributor iTurbo's Avatar
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    Re: Bosch 772 manual fuel pressure regulator replacement

    The fuel return port on the stock and Accufab regulators use a 14 x 1.5 metric thread with O-ring. Like Todd said, don't use a 1/4" NPT fitting even though it *seems* like it fits OK.

  4. #4
    Supporting Member Turbo Mopar Contributor zin's Avatar
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    Re: Bosch 772 manual fuel pressure regulator replacement

    There was a Bosch adjustable regulator that used to be sold by MSD (maybe still?...), I bought one, but I've never installed it, so I don't know if it's a bolt-in or not.

    My application was for an early T1, my aim was to have an adjustable reg, but still appear stock, thereby sneaking it past the "Smog Nazis" here in CA...

    Does this sound like the one you mention?

    Mike
    "The Constitution is not an instrument for the government to restrain the people, it is an instrument for the people to restrain the government - lest it come to dominate our lives and interests." - Patrick Henry

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  5. #5
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    Re: Bosch 772 manual fuel pressure regulator replacement

    There were others that made them over the years. I've seen one where the adjustable feature was inside of the vacuum/pressure port nipple (very stealthy). Others that had a metal plate riveted to end of regulator, and others still that used a billet cap with internal o-ring that bolted to regulator and were held in place with set screws. ATR the Buick and SVO aftermarket company had a beautiful aluminum one, but that company is long, long, gone.
    Todd
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  6. #6
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    Re: Bosch 772 manual fuel pressure regulator replacement

    Sorry All,

    For some reason I did not get the notifications that there were replies here. The application is a 1991 Spirit R/T. The 772 is the only part number I can see on the top side of the regulator.

    - - - Updated - - -

    Quote Originally Posted by 4 l-bodies View Post
    There were others that made them over the years. I've seen one where the adjustable feature was inside of the vacuum/pressure port nipple (very stealthy). Others that had a metal plate riveted to end of regulator, and others still that used a billet cap with internal o-ring that bolted to regulator and were held in place with set screws. ATR the Buick and SVO aftermarket company had a beautiful aluminum one, but that company is long, long, gone.
    Todd
    This is along the lines of what I have. The riveted on plate is leaking and I am looking to replace.

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    Re: Bosch 772 manual fuel pressure regulator replacement

    Is it possible to put a stock FPR back on the car and let the CPU handle the tune? Or am I already out of the range of a stocker at this point?

    TIII
    -57 trim T3/T4 Turbo from FWDperformance
    -FWD Performance Stage 3 Computer (18psi)
    -+40 (52 lb) injectors

    I tried posting a picture link but cannot seem to get the settings right from google photos.
    Last edited by dr_amx; 04-02-2019 at 11:58 AM.

  8. #8
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    Re: Bosch 772 manual fuel pressure regulator replacement

    Quote Originally Posted by dr_amx View Post
    Is it possible to put a stock FPR back on the car and let the CPU handle the tune? Or am I already out of the range of a stocker at this point?

    -57 trim T3/T4 Turbo from FWDperformance
    -FWD Performance Stage 3 Computer
    -+40 (52 lb) injectors

    I tried posting a picture link but cannot seem to get the settings right from google photos.
    You more than likely could put a stock FPR back on but depending on where the fuel pressure is set now, you could be right on, lean or rich. Have any idea where your static fuel pressure is set now? Stock is 52-55 PSI. BTW the Accufab regulator is rebuildable. If I were you, I'd just buy an Accufab and be done with it. Quick Google search they're around $140 shipped. They work fine.
    Todd
    Last edited by 4 l-bodies; 04-02-2019 at 12:26 PM.

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    Re: Bosch 772 manual fuel pressure regulator replacement

    I don't know the current fuel pressure. I will have to check. Since you guys have verified that the accufab works on a stock rail I will likely do that. Lots of little things to cleanup on this car.

    Thanks,
    Ben

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    Re: Bosch 772 manual fuel pressure regulator replacement

    Measured the fuel pressure last night. 42psi. The AccuFab also showed up but I still need to order some fittings. How thick do these washers need to be? With the 14mm adapter, is the o-ring near the tip or the hex? Maybe this is a good time to do all of my fuel lines.
    Last edited by dr_amx; 04-09-2019 at 11:05 AM.

  11. #11
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    Re: Bosch 772 manual fuel pressure regulator replacement

    I used to use 2) fairly thin washers on each stud. I then (as noted in post # 2) file the points off the hex fitting, then you don't need to use washers/spacers. More than one way to go from outlet of Accufab to 1/4" hose fitting. Pictured is AN way (3 fittings) and factories solution. The Chrysler fitting is 89-92 turbo 1 application. Part # is 4418662. The o-ring is shown on fitting in post #2.
    Todd
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  12. #12
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    Re: Bosch 772 manual fuel pressure regulator replacement

    Quote Originally Posted by 4 l-bodies View Post
    I used to use 2) fairly thin washers on each stud. I then (as noted in post # 2) file the points off the hex fitting, then you don't need to use washers/spacers. More than one way to go from outlet of Accufab to 1/4" hose fitting. Pictured is AN way (3 fittings) and factories solution. The Chrysler fitting is 89-92 turbo 1 application. Part # is 4418662. The o-ring is shown on fitting in post #2.
    Todd
    Thanks!
    Ben

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    Re: Bosch 772 manual fuel pressure regulator replacement

    Here is why I asked the question about the fitting and the o-ring position. http://www.fwdperformance.com/Store/...&ProductID=859 (Name: Fuel Fittings for Universal Regulator Part Number: FWD 7-0859 Description: Two fuel fittings for use with our universal Accufab regulator) These ones that FWDP sells appear to seal on the face and not the bore like the one pictured in post 2.

  14. #14
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    Re: Bosch 772 manual fuel pressure regulator replacement

    Not really sure what to make of FWDP catalogs part #'s listed. I can see how your perplexed. Shows picture of 7-0101. That looks like 1/4" NPT to 1/4" hose fitting with no o-ring. Just coincidental that 1/4" NPT screws into 14X1.50mm thread. Seal with Teflon tape? Picture of 7-0859 shows two fittings with AN o-ring boss thread? Then in Accufab description it notes; NOTE: 2 piece intake users require a brass fitting for fuel inlet, part number FWD 5-203. Inlet? Line coming out of regulator is actually the OUTLET or return going back to tank. No picture that I found of 5-203, or is that new/old part # for 7-0101?

    Look where factory return line o-ring is placed. That should tell you how factory dealt with sealing this fitting.

    FYI the O-ring on factory and AN fittings uses a difficult to track down O-ring. The correct O-ring part # is Standard Motor Products (SMP) SK18. Probably not going to find that at your local hardware store.
    Todd

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    Re: Bosch 772 manual fuel pressure regulator replacement

    Thanks again Todd!

    Ben

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    Re: Bosch 772 manual fuel pressure regulator replacement

    Quote Originally Posted by dr_amx View Post
    Thanks again Todd!

    Ben
    Glad to help Ben. Good luck with your project.
    Todd

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    Re: Bosch 772 manual fuel pressure regulator replacement

    I finally got around to changing the regulator. I set the pressure back to about 44psi without the vacuum line. I also put in a new AFR. The AFR is going down to 11-10 when in a little boost. Do I need more fuel pressure?

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    Re: Bosch 772 manual fuel pressure regulator replacement

    Quote Originally Posted by dr_amx View Post
    I finally got around to changing the regulator. I set the pressure back to about 44psi without the vacuum line. I also put in a new AFR. The AFR is going down to 11-10 when in a little boost. Do I need more fuel pressure?
    If I recall correctly, 11.5 is the safe spot, 12 works great, but not as safe. If you are dipping into the 10s, it's a bit rich. But I believe the FWD Calibrations tend to run on the rich side to prevent people from popping engines.

    In theory, the FWD Stage 3 computer should be expecting 55psi base pressure, but I would hazard a guess that you don't want to turn it up if you are already running a bit rich.

    When measuring AFR, are you at WOT or part throttle?

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    Re: Bosch 772 manual fuel pressure regulator replacement

    Oh, I was thinking that 14 was the safe spot. I guess I have it backwards. The Innovate AF gauge reads constantly. I was watching it as I accelerate so part throttle not WOT.

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    Re: Bosch 772 manual fuel pressure regulator replacement

    Quote Originally Posted by dr_amx View Post
    Oh, I was thinking that 14 was the safe spot. I guess I have it backwards. The Innovate AF gauge reads constantly. I was watching it as I accelerate so part throttle not WOT.
    14.5 is the perfect mix for air/fuel for fuel efficiency, but will blow your engine up at WOT. The higher the number, the more lean you are running.

    Check it at WOT, as part throttle, I believe, still uses the 02 input to determine fuel amount instead of just referring to the WOT map in the computer. It may lean out to a 12:1 at WOT.

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