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Thread: Primary Fuel Pressure Regulator

  1. #1
    Member
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    Primary Fuel Pressure Regulator

    Hi.
    I have had a lot of problem with fuel pressure. What I see now is that the PPR seem to be blocking the return from the WUR, so the control pressure and primary pressure are the same.
    If I take the return line from the WUR, off the fuel distributor fuel are flowing and the values looks ok. If I turn the PPR out far enough the fuel will flow. Turning it in again it stops. Do anybody have an idea what could lead to this?
    The return line to the fuel tank is open.

  2. #2
    Senior Member Bitsyncmaster's Avatar
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    When I had both pressures the same, it was my WUR was bad. But check your WUR inlet screen to see if it's clear.
    Dave M vin 03572
    http://dm-eng.weebly.com/

  3. #3
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    Very common for the WUR aka Control Pressure Regulator (CPR) to fail. If you search the internet there are ways to fix it or you can send yours out for repair. The Primary Pressure Regulator (PPR) doesn't typically fail that way, when it fails you have hot restart problems. Try to put the PPR back to the setting you had, even if it is off a little bit it should be OK and you can fine tune it after you get the CPR fixed. Make sure the return line to the tank is not blocked, kinked, or plugged up again. Many of the problems with the fuel system start in the fuel tank. Make sure it is clean, all of the boots are still rubbery, everything is in proper position, and the pump is good especially if you are still using the OEM pump set-up.
    Last edited by David T; 05-14-2024 at 08:59 PM.
    David Teitelbaum

  4. #4
    Motors about after dark Michael's Avatar
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    I will just say that my Dgo WUR and FD fixed a lot of issues with my car.


    When I pulled and resealed the intake a few months ago, that's when I experienced true rock solid cold start up and idle. I would trust this car anywhere now.
    http://dmctalk.org/image.php?type=sigpic&userid=90&dateline=161808992  9

  5. #5
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    I put the Dgo WUR in last year. The fuel flows fine out of the WUR, it can,t pass the fuel distributor for some reason. The return hose/pipe to the tank is open.

  6. #6
    Administrator Ron's Avatar
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    Quote Originally Posted by Slammer View Post
    I put the Dgo WUR in last year. The fuel flows fine out of the WUR, it can,t pass the fuel distributor for some reason. The return hose/pipe to the tank is open.
    FWIW- There is a small passage between the FD's port for the CPR/WUR line and the return to tank port. A piece of old PPR o-ring got into the passage on 1669 and made it act as you describe (CPR/WUR couldn't bleed off fuel to get proper control pressure).

  7. #7
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    Quote Originally Posted by Ron View Post
    FWIW- There is a small passage between the FD's port for the CPR/WUR line and the return to tank port. A piece of old PPR o-ring got into the passage on 1669 and made it act as you describe (CPR/WUR couldn't bleed off fuel to get proper control pressure).
    That's about what I thought.
    Any way I can get to that passage without dismantling the hole thing?

  8. #8
    Administrator Ron's Avatar
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    Quote Originally Posted by Slammer View Post
    That's about what I thought.
    Any way I can get to that passage without dismantling the hole thing?
    Yes. Remove the PPR, CPR/WUR return hose, and the FV-return to tank hose from the FD. Then you can see/figure out where the passage is. All return winds up in that corner...

  9. #9
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    Quote Originally Posted by Ron View Post
    Yes. Remove the PPR, CPR/WUR return hose, and the FV-return to tank hose from the FD. Then you can see/figure out where the passage is. All return winds up in that corner...
    That's what I did. Everything looked fine, until I put the PPR back. It was blocked again.
    Decided to try another FD, and it seemed ok except the pressure was to low. I then added shims to get the pressure up, but ended up with the same problem. Took out some of the shims, and the control pressure was back.
    So is it possible to get the engine to run properly with 3,6 bar primary pressure?

  10. #10
    Senior Member Bitsyncmaster's Avatar
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    Quote Originally Posted by Slammer View Post
    That's what I did. Everything looked fine, until I put the PPR back. It was blocked again.
    Decided to try another FD, and it seemed ok except the pressure was to low. I then added shims to get the pressure up, but ended up with the same problem. Took out some of the shims, and the control pressure was back.
    So is it possible to get the engine to run properly with 3,6 bar primary pressure?
    I don't think 3.6 bar would ever run the engine properly. With only 52 psi primary pressure and your control pressure at 50 psi it just would never run right.
    Dave M vin 03572
    http://dm-eng.weebly.com/

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