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Fox Body Fairmont 3V Motor Swap: FRPP Controls Pack & Fuel Install

Created by Jeff Jimenez
Date Created: 11/28/2013
Last Updated: 9/23/2021

Check out the install of Ford Racing's harness & controls pack, as well as the fuel system on LMR's Fox Body Fairmont 3V Motor Swap.

Viewing this install and using the information shared is subject to the terms set forth here - View the LMR Install Instructions Disclaimer.

FOLLOW: mustang , 79 93 mustang , fox body , installation , ford racing , project car , 3v fairmont

If you've been following along, you know that the Ford Racing Hot Rod 3-valve 4.6 has found its place in our '79.  The k-member has been swapped, the Mustang long tube headers have been affixed to the engine via Logan Motorsports adaptors, the Quick time bellhousing has been installed with the Ram clutch, and the motor was lowered into place on urethane motor mounts.  A little coaxing with the headers and Maximum Motorsports k-member spacers have brought us to a third blog. 

Now we have to install the Ford Racing harness and controls package, as well as the fuel system, finish the cooling system, and put the Tremec TKO 600 transmission in.

Ford Racing Controls Pack Installation

As I've discussed in previous blogs, Ford Racing, with the help of Dunne-Rite performance have made the wiring portion of this install a breeze.  No longer is the need for wiring manuals, schematics, custom tuning or laborious research.  The hardest part of installing the harness and controls package is mounting the gas pedal, computer and relay box.  Once everything was in place, it was plug-and-play. 

The Hot Rod 3-valve comes with its engine harness installed.  The engine harness has plugs that attach to the Ford Racing harness, as well as the computer, and it has a large buss connector that bolts inside of the relay box.  The relay box supplied by FRPP has fuses and relays that power the fuel pump, fans, starter relay, and intercooler pump if so equipped.  The Ford Racing harness simply plugs into the relay box.  I hope I'm not sounding too vague, here, but all of the plugs only connect one way.  The kit really is that self-explanitory.  The relay box has one 10 gauge red wire that will hook to a battery power source.  I hooked this red wire to the large battery pole on my factory solenoid. 

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Continuing onto the harness, a 10 gauge orange wire is labelled as the power for your electric fans.  I hooked this wire to the positive wires on my Mishimoto dual fan kit.  The ground wires for the fan were grounded to the body of the car. 

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 Also in the FRPP harness are a large, 10 gauge black ground wire that will need to be connected to the engine block or negative battery terminal, as well as a smaller 16 gauge chassis ground wire.  Inside the car, the Ford Racing engine and controls package has 16 gauge wires for hot in start and run (red with green stripe), as well as a hot in start only (red with blue stripe).  Both of these wires I connected directly at the ignition switch.  Ford veterans will recognize the wire coloring.  Most Ford wiring carries the same coloring over the years to make for easier troubleshooting.  The Ford Racing harness is the same.  The red with blue stripe start wire will match the red with blue stripe wire from your ignition switch.  The red with green wire was hooked to the red keyed hot from the ignition switch. 

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 Ford Racing has included a clutch start wire that must be hooked to a clutch safety switch or grounded.  Other wires inside the car are a tan with yellow stripe that hooks to your tachometer, as well as an a/c clutch switch if you're retaining air conditioning, and a vss speed signal wire that you likely won't use.  The final wire that must be attached is a green fuel pump power wire, that I ran through the inside of the car to the in-line BBK EFI fuel pump. 

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The ground for the pump was attached to the body of the car.

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 Pictures show how I ran the harness from the accelerator pedal along the firewall below the windshield, then through a factory oval harness grommet I scabbed from an old scrap harness.

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  The harness hole was made with a 1.25" holesaw, then completed with a cutoff wheel.  I ran the harness through the passenger side panel behind the dash because I don't plan to run a/c or heat.  If your fox is an 83 or later model, you can run the harness through the factory grommet's location in the firewall. 

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 The remainder of the harness ran along the inner fender structure on the passenger side.  I mounted the computer in the inner fender, on the back side of the fender apron. 

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 I attached it with an extra fender bracket, a piece of angled aluminum, and factory-style fender bolts and speed nuts.

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  The relay box was mounted inside the engine compartment with sheetmetal screws, beneath my aluminum overflow can part number Overflow catch can

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 The FRPP cold air that was provided with the kit was used, sans the heat shield that was designed for an 05-09 Mustang.

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 My trunk mounted battery was grounded to the flange on the inner wheel well, and the positive battery cable was run to a remote shutoff, through the interior, through the harness grommet for the computer harness, and to the starter solenoid in the inner fender.  The FRPP harness and controls package eliminates the need for a solenoid, because the relay box  switches the starter.  My solenoid simply serves as a power junction for the battery cable, power to the relay box, and power to the car's harness.  The large cable for the starter also hooks to this junction.  The small trigger wire for the starter is yellow with a blue stripe, and located on the engine's harness.

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Fuel system:

I wanted to to simplify the installation of the fuel system by retaining the car's original feed and return lines, as well as the original fuel tank.  This car was carbureted from the factory, so I had to use the aformentioned BBK in-line pump.  The plumbing at the rear of the car was fairly straightforward.  A combination of the BBK-supplied connectors, a used, factory 87-93 fuel filter and bracket, some high-pressure EFI fuel line, and some worm clamps got it done.  The pump was hooked to the factory sender, then plumbed to the filter, then to the factory metal fuel line.  The return hooked up with no changes other than a new piece of hose. 

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At the front, I cut the lines off closer to the firewall to eliminate interference with the suspension.  I wanted to use as little rubber line as possible, so I had a friend braize on -6 and -4 AN fittings to the factory metal line. 

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 I finished the fuel system outsite with Aeroquip snap-lock line, and fittings.  Two bulkhead fittings provided connections for inside the engine compartment, where I used -4 return and -6 pressure line from the bulkheads to the Professional Products 2-port return-style regulator.  I finished the engine compartment off with more braided line, by using a -8 from the regulator to the AN adaptor that allowed it all to snap together with the factory 05-09 non-return rails. 

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There are certainly more ways to do your fuel system, but I felt this was the easiest for my application.  Big, braided lines or snap-lock lines from the tank all the way up might have been better, but my stock lines were the same size as 87-98 return-style systems, which are good for near 500 rwhp.  I also wanted to use the factory un-modified tank.  If later plans call for forced induction, an upgrade in line size and pump is easily accomplished.  If you're performing this swap on a car originally equipped with an in-tank pump, that pump can still be utilized, along with the factory lines and a similar under-hood setup using a return-style regulator and the factory non-return rails.

 The transmission installation was straightforward, with the exception of the crossmember and the driveshaft.  My car was originally equipped with a C4.  The longer Tremec TKO 600 required shortening the driveshaft, which was done at a local driveline shop.  They also installed a conversion u-joint to mate the 31-spline yoke to the smaller shaft.  79-81 Mustangs and other fox bodies use narrower transmission crossmember brackets.  This presents a problem with the Tremec because you can't simply slide the crossmember backwards as you can on an 82-93 Mustang.  My solution was to mount the crossmember on the backside of the factory brackets, and fabricate a new flange for the rear of the crossmember.

The cooling system consists of the aluminum radiator and fan package, along with factory 07-09 Mustang upper and lower radiator hoses.

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  The factory lower hose has a tee in it that supplies a smaller hose to the factory 07-09 Mustang overflow bottle.  I wouldn't be using this, so I opted to replace the tee with an Autometer ATM-2283 gauge adaptor.  This adaptor eliminates that unsightly tee and provides a 3/8" NPT hole for a gauge sender for the Autometer water temp gauge I'll be installing later.  The heater hose connections on the engine were simply plugged with 5/8" and 3/4" bypass plugs I sourced from the local parts store.

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 Well, there you have it.  If you've looked at your checklist, you'll know that I now have fuel, ignition, starting, cooling and drive systems all in place.  It should run, right?

 Yes!  but you'll have to stay tuned to hear it......


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1979-93 Mustang Computers, Tuners & Control Packs