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  1. #1

    Cool Fuel pump wiring?

    does any one have a guide for wiring the fuel pump for a stable 12v some what like for the head lights on the 4 eyes

  2. #2

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    Where are you at? Are you working on an EFI conversion or a carb fuel pump setup?

  3. #3

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    No this would be for the 86-93 Fi cars and it's a 88 thought I have seen a guide some where in the past
    For this don't remember where it was

  4. #4

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    Isn't the factory FP relay and harness working?

  5. #5

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    It is while every thing seems to check out the pump is running but it's speed is not constant at idle

  6. #6
    Moderator wraithracing's Avatar
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    Quote Originally Posted by darko View Post
    It is while every thing seems to check out the pump is running but it's speed is not constant at idle
    If everything is working, then the odds are the pump may be failing. Otherwise you would want to check your grounding to make sure you don't have an issues there. You could try attaching a volt meter to the fuel pump wiring and verify if the voltage is changing while at idle. If not, then I would definitely suspect a pump going bad. Good Luck!
    ​Trey

    "I Don't build it hoping for your approval! I built it because it meets mine!"

    "I've spent most of my money on Mustangs, racing, and women... the rest I just wasted."

    Mustangs Past: Too many to remember!
    Current Mustangs:
    1969 Mach 1
    1979 Pace Car now 5.0/5 speed
    1982 GT Stalled RestoModification
    1984 SVO Still Waiting Restoration
    1986 GT Under going Wide Body Conversion Currently

    Current Capris:
    1981 Capri Roller
    1981 Capri Black Magic Roller Basket Case
    1982 Capri RS 5.0/4spd T-top Full Restoration Stalled in TX
    1984 Capri RS T-top Roller
    1983-84 Gloy Racing Trans Am/IMSA Body Parts

  7. #7

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    Agreed...if it's working at all the wiring is not likely the culprit. These are pretty simple and robust systems. Pump's probably full of rust or just old and wearing out.

  8. #8

    Cool

    Pumps new put in on 12 23 19 the old pump was doing this
    Put in a 242 walbro and it was doing this as well when first put in
    Doesn't seem to be doing it now checked when changing the vss
    Last edited by darko; 01-01-2020 at 08:55 PM.

  9. #9
    Moderator wraithracing's Avatar
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    Quote Originally Posted by darko View Post
    Pumps new put in on 12 23 19 the old pump was doing this
    Put in a 242 walbro and it was doing this as well when first put in
    Doesn't seem to be doing it now checked when changing the vss
    I would double check your ground wires for the system. Sounds to me like an intermittent grounding issue. When the ground is solid the pump works as it should, when the ground is weak, the pump slows down and you get that cyclical speeding up and down issue. Good Luck!
    ​Trey

    "I Don't build it hoping for your approval! I built it because it meets mine!"

    "I've spent most of my money on Mustangs, racing, and women... the rest I just wasted."

    Mustangs Past: Too many to remember!
    Current Mustangs:
    1969 Mach 1
    1979 Pace Car now 5.0/5 speed
    1982 GT Stalled RestoModification
    1984 SVO Still Waiting Restoration
    1986 GT Under going Wide Body Conversion Currently

    Current Capris:
    1981 Capri Roller
    1981 Capri Black Magic Roller Basket Case
    1982 Capri RS 5.0/4spd T-top Full Restoration Stalled in TX
    1984 Capri RS T-top Roller
    1983-84 Gloy Racing Trans Am/IMSA Body Parts

  10. #10

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    I would check voltage at the pump. And compare it to voltage at the battery
    On my turbo tbird, I discovered that the inertia switch connector had melted and the pump was seeing a full volt less than the rest of the car. I couldn't see the melted part of the connector because it was up inside the inertia switch.
    Just something else you could check
    You could also use the stock fuel pump wiring to trigger a relay and just run a dedicated 12v line from the battery to the back

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