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  1. #1

    Default Holley 4180 fuel pressure

    I am working on my '85 Capri RS fuel system. Can anybody tell me how much fuel pressure a 4180 likes to see? I am running an 80 gph Holley mechanical pump. Holley says it doesn't need a regulator but I have a feeling I am going to need one.

  2. #2
    FEP Senior Member droopie85gt's Avatar
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    6 or 7 psi is enough.
    1985 GT, Sunroof, 5 Lug, Rear Discs, 01 Graphite Bullets, 88 forged piston shortblock, 2.02/1.60 Alum heads, Weiand Stealth, Holley C950 TBI, BBK Long tubes

  3. #3

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    Yeah I was thinking maybe the new fuel pump was putting out too much pressure. I need to make up a gauge and see where it is at.


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  4. #4
    FEP Super Member bwguardian's Avatar
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    Is the fuel return line off the pump back to the tank in working condition?
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  5. #5

    Default Holley 4180 fuel pressure

    Well with the Holley pump it doesn’t have a return provision. A little back story on the set up. I pulled the motor and put on a different set of heads and cam. I switched the factory fuel pump to the Holley 80gph pump and now the car won’t idle and is fouling out the plugs. I have a 600 double pumper That will be going on, I just put the stock carb back on to get it fired up and running.


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    Last edited by Adriver; 09-27-2018 at 03:59 PM.

  6. #6

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    5-6psi... or lower, and bigger needles and seats for adequate fuel delivery without frothing in the bowls from excessive pressure, is best. The quick and easy way to tell if you have excessive fuel pressure is to look at the float/fuel levels in the float bowls after the pump change. If they were previously correct and now they are higher, because the floats need to exert more pressure upward to shut off the incoming fuel... there's your issue. Does the car have or still have a return provision, a return line to the tank? Find out what the as is dead-heading pressure of the way it is now is, and if it's too much, make your own damn return between the pump and carburetor with a T with a sized restriction (1/16", 1/32", etc) inside it, connected to your return line... see my build thread for how I made one for with a low pressure in-tank electric fuel pump to get the fuel pressure exactly where needed.
    Last edited by Walking-Tall; 09-27-2018 at 05:06 PM.
    Mike
    1986 Mustang convertible ---> BUILD THREAD
    Past Fox-chassis "four eyes":
    1983 Mercury Cougar LS
    1986 Ford Thunderbird ELAN
    1980 Capri RS Turbo

    Work in progress website ---> http://carb-rebuilds-plus.boards.net/

  7. #7

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    Cool, I’ll check that out. Thanks.


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  8. #8

  9. #9

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    Hooked the regulator last night. After messing with the car I finally got it to idle. Still isn’t even close to being right, but it is a start. For some reason the regulator doesn’t want to let me adjust the fuel pressure much. I had it at 5 now I can’t get it to adjust back up to 5. Kinda has me thinking the regulator is junk, which would be just my luck


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  10. #10

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    Quote Originally Posted by Adriver View Post
    Hooked the regulator last night. After messing with the car I finally got it to idle. Still isn’t even close to being right, but it is a start. For some reason the regulator doesn’t want to let me adjust the fuel pressure much. I had it at 5 now I can’t get it to adjust back up to 5. Kinda has me thinking the regulator is junk, which would be just my luck


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    Get a good autometer gauge. I have a reg and gauge installed on my holley equiped 302 that stays on the car. Great for diagnosing problems sometimes.
    Mine is set to 6psi. If you change pressure recheck floats every time.

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