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Thread: Low fuel pressure

  1. #1

    Default Low fuel pressure

    In my quest to shorten my cranking time Ive uncovered another issue. When I turn the key, the fuel pressure shoots up to about 40psi then falls to about 10psi and stays there. Then while running the fuel pressure is about 30psi but will jump to 40 psi with the regulator unplugged. I tested the fpr with the car off and it holds vacuum. Does it sound like the check valve in the fuel pump? If so its a shame because it is still strong. Maybe a leaky injector? I did smell some raw fuel around the passenger side valve cover when I cycled the key however that could just be from the shrader valve since my fuel pressure tester was still installed.


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  2. #2
    I'm an air-conditioned gypsy gadget73's Avatar
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    Default

    If you have a leaky injector I'd expect one or more of the plugs to be wet or at least look obviously darker in color than the others.

    If the pressure drops after the pump stops, thats a leak somewhere. Could be the pump, could be the hose in the tank.

    86 Lincoln Town Car (Galactica).
    5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

    91 Lincoln Mark VII LSC SE, triple black (Timewarp) - poly front bushings, KYB struts and shocks, Holley SystemMax1 lower intake, SilverFox AOD valve body,

    1984 Lincoln Continental TurboDiesel - rolls coal

    Quote Originally Posted by phayzer5 View Post
    I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

  3. #3

    Default

    My fuel pressure tester died earlier (figures) as I was trying to narrow it down. The injectors are supposed to be rebuilt so Im ruling that out for now. I need to buy new fuel rails since the nos ones I got are bent (theres a recall from the 80s on that lol) so I can test the injectors then. Im leaning towards fuel hose in the tank. I hate to drop the tank but it looks like Im going to have to. Ill have a new pump on standby just in case.


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  4. #4
    I'm an air-conditioned gypsy gadget73's Avatar
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    there is a recall for bent rails?

    They're just steel tubing, if its not too awful you should be able to bend it back. I've tweaked them and then un-tweaked them in the past.

    86 Lincoln Town Car (Galactica).
    5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

    91 Lincoln Mark VII LSC SE, triple black (Timewarp) - poly front bushings, KYB struts and shocks, Holley SystemMax1 lower intake, SilverFox AOD valve body,

    1984 Lincoln Continental TurboDiesel - rolls coal

    Quote Originally Posted by phayzer5 View Post
    I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

  5. #5

    Default Low fuel pressure

    I remember reading about it a while ago, funny that my nos ones are apparently pre-recall units. Though I could be mistaken. However they are bent. I thought about tweaking them myself but was too afraid. Gadget youve never led me astray so Ill try it lol. Thanks.

    Edit: Found it

    https://www.automd.com/recall/campaign_c26252/

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    Last edited by 87GrandMarq; 10-14-2019 at 09:57 PM.

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