Stock Fuel Pump Wiring Upgrade - Modular Fords

  • Stock Fuel Pump Wiring Upgrade

    Ok, here is a complete step-by-step how to with pics/ explanations and parts necessary to help lower the amperage draw on the stock pumps to reduce pump duty cycle...a potential alternative to the BAP for those who are on the ragged edge of the stock system.

    Credit on this goes to MJ, and Dustoff... and thanks to stlblack03 (Randy) for the help/ hand modeling...

    Here goes:

    Pick up some 10 guage (8 guage will work as well) wire. 20 feet will do it.

    Assorted quick connects:



    A 20/30 ampor 5 postion relay ( w/ pins 30, 85, 86, and 87 )




    30 AMP inline fuse



    ( I soldered everything I could, but wire connection is your choice )... Solder your 20 foot power wire to the 30 amp inline fuse



    DISCONNECT BATTERY!!! Locate the power distribution block just in front of the battery.



    Attach 30 amp inline fuse to nut at power distribution block...



    Feed other end of power wire through firewall at grommet on driver's side. A metal coat hanger taped to the end of the wire helps accomplish this. Once through, meander the wire down the kick panel, door sill, rear seats, and back to rear kick panel...



    Remove rear kick panels exposing the FPDM and FPDM harness... Your relay will be mounted right next to the FPDM.



    Hold relay up for visualization to the FPDM and cut the power wire at the correct length. Save the rest, you will be using it later. Solder the power wire to pin #30 on the relay...



    Remove electrical tape and loom from factory FPDM harness. Expose about 6-8 inches to allow yourself room to work. Locate the brown/pink stripe AND green/yellow stripe wires. (Randy makes a great hand model!!!)



    Ok the next part is a little lengthy, but stay with me. First, cut the green and yellow strip wire ( yes cut it ! ) Leave yourself enough room at both ends of the cut to work with. You now have two ends of wire:

    1) One end leads to the FPDMharness (we will call the short wire)

    2) The other end leads back into the wire loom, to the front of the car, to the CCRM. ( we will call the long wire )

    1) Solder the short wire coming from the FPDM harness to PIN 87 on your relay

    2) Solder the long end of the wire (going to the CCRM) to pin 86 of relay

    This is where you will use your remaining piece of power wire. Next, splice into the brown/pink wire via the quick connect with the rest of the power wire.



    Another view...



    Now the fun and hardest part of this mod...dropping the tank. This part is not too bad to be honest. JUST MAKE SURE YOUR TANK IS CLOSE TO EMPTY. We did two of these this weekend. One was easy, one was way too hard. One tank was empty, one was full. (A-A-Ahem, Randy ) Jack the car up and support on jackstands. Remove driver's side rear wheel. We used a small cart to help support the tank as we dropped it.



    Unbolt the tank straps ( three 13mm bolts) and the small filler neck bracket (8mm shown here). It helps to have 2 people to do this, to help support the tank.



    Once the last bolt is out, carefully lower the tank. You only need to lower it about 6-10 inches to have access to what you need. The tank could probably suspend by itself, but I would get something under it for support to be safe. As you lower the tank, a fitting ( I believe it is the tank vent ) will come undone. Make sure to re-attach this when lifting the tank back in. You will have sufficient access to this with the rear wheel off.



    Now that the tank is lowered, you can see the wiring harness...



    Locate the brown/pink wire off the harness. On both of our cars, it was the second from the front.



    Fish the other end of the power wire that is connected to the brown/pink wire at the FPDM down through the weather proof tape in the spare tire well...



    Again, use a quick connect witht the power wire to splice into the brown/pink wire at the tank. Some like to use di-electric grease here. Once connected, wrap with electrical tape.



    Reinstall tank, filler neck bracket, and the vent tube. Put the wheel back on, and lower the car.

    Attach a ground wire from pin # 85 of the relay to the same ground as the FPDM.



    Neatly zip-tie everything together and mount the relay. Replace your kick panels and connect battery.



    That's it! Good luck.
    This article was originally published in forum thread: Stock Fuel Pump Wiring Upgrade started by BLK_03 View original post
    Comments 80 Comments
    1. hj16's Avatar
      hj16 -
      You could really use some more pictures Tony
    1. quadcammer's Avatar
      quadcammer -
      how do you solder the wire to the pins on the relay?

      also, you did not cut the brown/pink wire right?

      since i have the bap, should i tap into the pink/brown before the bap, or after it.
    1. 88lx418's Avatar
      88lx418 -
      Quote Originally Posted by quadcammer View Post
      how do you solder the wire to the pins on the relay?

      also, you did not cut the brown/pink wire right?

      since i have the bap, should i tap into the pink/brown before the bap, or after it.

      I was going to ask the same thing, it appears in one photo that the brown and pink wire was cut, but you just tap into it twice correct?

      Nice write up
    1. 04-VENM's Avatar
      04-VENM -
      Good info. I call you if I have a problem. If I get a bap this shouldnt be a problem?
    1. BLK_03's Avatar
      BLK_03 -
      The relay has a wiring harness that attaches to it. Look at the pics. It is a two piece deal. One pic shows it w/ the harness on, one pic shows it w/ the harness off (the close up).

      I did NOT cut the brown/pink wire. Just spliced into it with the quick splice connectors...twice.

      Not sure how all this works with the BAP. I did this in an effort to stay away from the BAP.
    1. fusion_ta66's Avatar
      fusion_ta66 -
      Thanks for the great write-up. I have a question: Can't you access the pump wiring harness through the weather-proof tape hole in the trunk? Isn't that what that is there for? Access to the pump? Just curious.

      thanks
      Joe
    1. BLK_03's Avatar
      BLK_03 -


      I'm not sure if you can access the tank through there or not. But holy hell, that would make things easier...lol
    1. Bryan's Avatar
      Bryan -
      Wow, very nice write-up I must say! I'm not sure if I am going to do this mod, but it will sure be easy to do with the help of this thread. I really don't like the idea of using quick splice connectors to join small wire to a large guage wire, but I guess there is no other way.

      Is this mod a replacement for the BAP, or can it be used in conjunction with it? Hell, anyone doing this mod might as well pick up one of those fuel line kits while the tanks is dropped!
    1. BLK_03's Avatar
      BLK_03 -
      I would have to say that this mod is for those that are on the brink of maxing the stock system. This will give you 8-10% more with the pumps. I wouldn't call it a "replacement" for the BAP, just something to try if you don't like/ don't want to do a BAP.
    1. stlblack03's Avatar
      stlblack03 -
      Quote Originally Posted by fusion_ta66 View Post
      Thanks for the great write-up. I have a question: Can't you access the pump wiring harness through the weather-proof tape hole in the trunk? Isn't that what that is there for? Access to the pump? Just curious.

      thanks
      Joe
      If this is true I'm gonna kick your ass Tony
    1. fordfan's Avatar
      fordfan -
      Is that relay NO(normally open) or NC(normally closed)?
    1. Dana's Avatar
      Dana -
      Quote Originally Posted by fordfan View Post
      Is that relay NO(normally open) or NC(normally closed)?
      That style relay has both types of contacts NO & NC.

      Nice write up!!!

      I would prefer soldering all the connections that you made. Those crimp on connectors can be trouble down the road.

      Mine has been in and modded similarly for over a year and a half with no problems.


      Dana
    1. jackers's Avatar
      jackers -
      Dude, you should pm a moderator and get this thing a perminent home on the Reference Forum. Another great write up from this site. Good Job!
    1. Wilson & Co.'s Avatar
      Wilson & Co. -
      thanks for pics..

      Someone please put this in the reference forum.

      edit...guess i spent 4 mins reading it before posting..
    1. lRageATMl's Avatar
      lRageATMl -
      why not cut the brown pink wire? you are essentially replacing it with the 8awg wire anyways...mine is already cut since I have a BAP installed and on mine on teh output side of the BAP I am going to run the 8AWG wire as well.

      i also prefer but connecters rather then those snap connectors...nice write up though!
    1. fordfan's Avatar
      fordfan -
      Has anybody just run 8 awg wire directly to the fuel pump assy? Might be a good idea if doing wire upgrade and 1/2 inch fuel line at the same time.
    1. 2kbill's Avatar
      2kbill -
      Quote Originally Posted by Wilson & Co. View Post

      Someone please put this in the reference forum.
      Will copy it there in a couple of days, in case there's more worthwhile additions.

      Bill
    1. 03Steve's Avatar
      03Steve -
      Use both wires instead of one. More conductive.

      Good write up Tony! When did all of this happen? Wish I could have been there.
    1. trmn8r's Avatar
      trmn8r -
      Nice write up and pictures guys. May be just the upgrade I need. My currnets mods show a peak of 94% duty cyle at wot. I just sent my blower out to have the port updated along with the TB/plenum ported. When they come back I will probably HAVE to install the HBH spacer while everything is apart. I'm sure with these mods added I will be over the edge of what the stock fuel system is capable of.

      Has anyone done before and after testing to confirm how much of a change in duty cyle this mod produces.
    1. stlblack03's Avatar
      stlblack03 -
      Quote Originally Posted by trmn8r View Post
      Nice write up and pictures guys. May be just the upgrade I need. My currnets mods show a peak of 94% duty cyle at wot. I just sent my blower out to have the port updated along with the TB/plenum ported. When they come back I will probably HAVE to install the HBH spacer while everything is apart. I'm sure with these mods added I will be over the edge of what the stock fuel system is capable of.

      Has anyone done before and after testing to confirm how much of a change in duty cyle this mod produces.
      Maybe Dustoff or MJChip can chime in. They have done some datalogging before and after I believe
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