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  1. #1
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    High fuel pressure

    Hi folks, I'm getting a high fuel pressure reading at the rail on my 1998 v70 t5. It is 65psi at idle but 43.5 when just primed and engine off. I have fitted a new fpr and checked return line for blockages. The fuel filter is newish and I have a new walbro pump. Been doing some logging and it is causing the fuel trim to lean out so I need to get to the bottom of the issue. Anyone had anything similar or got any ideas? Cheers

    Gareth

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    I'd start by double checking spec of new fuel pump fitted and also cleaning injectors, but no clue really in this area.

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    Have you checked the vacuum line from the manifold to the FPR?
    1996 Olive Green 850 AWD - Follow the Project - Forged rods, 19T, big blue injectors, 960 TB, 3.25" MAF, Ostrich, 608 binary, arduino data display, active exhaust control with Focus RS tips, 320mm front brake conversion.
    1996 Nautic Blue 850 AWD - Failed its MOT, now it's a donor for the green thing.

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    So the vacuum line is absolutely fine. I have put in an adjustable high flow replacement fpr but can't get idle pressure below 4bar. At an absolute loss as to why this would be happening. Injectors are new too. Granted it is a walbro 255 and not a standard pump but I can't find any documented evidence of this happening to anyone else

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    Was the pressure high before changing the injectors or fuel pump? Or any recent work done to the fuel system other than that?
    1996 Olive Green 850 AWD - Follow the Project - Forged rods, 19T, big blue injectors, 960 TB, 3.25" MAF, Ostrich, 608 binary, arduino data display, active exhaust control with Focus RS tips, 320mm front brake conversion.
    1996 Nautic Blue 850 AWD - Failed its MOT, now it's a donor for the green thing.

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    I didn't check it before changing the pump unfortunately. This has come to light after doing some logging and the fuel trim is too rich which is causing it to lean out at the top end. So this started the hunt for the problem and sure enough fuel pressure is too high. It was at 65psi and the adjustable high flow return fpr has helped me cap it at 55psi. But it is acting in the opposite manner to what it should. 55psi at idle under high vacuum and then drops when revving. I was under the impression it should be the other way around.

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    Is it possible you have the mixed up the flow and return lines when reconnecting after changing the fuel pump?

    Would make sense as the lines have the same size connectors onto the tank. And even more sense if the FPR is working in reverse (not being able to regulate the flow).

    I'd put the old FPR back in and swap the two lines over on the tank and see if that solves the issue.
    Last edited by Dangerous Dave; Thursday 28th May 2020 at 01:31.
    1996 Olive Green 850 AWD - Follow the Project - Forged rods, 19T, big blue injectors, 960 TB, 3.25" MAF, Ostrich, 608 binary, arduino data display, active exhaust control with Focus RS tips, 320mm front brake conversion.
    1996 Nautic Blue 850 AWD - Failed its MOT, now it's a donor for the green thing.

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    Hi the lines are definitely on the correct way. Could a blocked evap system cause high pressure?

    Sent from my SM-G960F using Tapatalk


 

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