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Swapping 6.9L for a 7.3L

Discussion in 'Ford Trucks' started by DJC, Nov 25, 2011.

  1. DJC

    DJC Senior Member
    Messages: 481

    I have a 86 F250 with a 6.9L in it and I would like to swap it out for a 88 7.3L that I already have. I have been doing a lot of searching but I still can't find the answer I'm looking for. How do I change the wire harness?? Reason being is the 6.9 only has 6 wires at the plug-in and the 7.3 has 12. Does anyone know how to match the colors up and where the other wires go and come off from the 7.3?? Thanks in advance for any help.
  2. Milwaukee

    Milwaukee 2000 Club Member
    Messages: 2,180

    They same

    But why you want swap? They are almost alike.

    Just REV to 3K rpm it will do work. Just reminder check oil level and change oil often.
  3. sparksrides

    sparksrides Senior Member
    Messages: 162

    try powerstrokenation.com might be some one who is familiar with the harness and maybe some one who has done the swap, I know they have a section for the 6.9/7.3 idi
  4. Silverstreak

    Silverstreak Senior Member
    Messages: 168

    what kind of 7.3? same vintage? you just have the fuel shutoff, oil pressure and coolant sensors, and the glow plug relay kick on and not sure if the power wire runs through it too for that solenoid. fuel heater, the 6.9 has one mounted on the pipe from the filter tower, i believe the 7.3s are the same way until the powerstroke era when you have the bowl. id just follow the wires. must be the alternator, the 7.3 has an internally regulated alternator, my 6.9 has the regulator mounted on the pass fender wheel well

    ..i personally woulda stuck with the 6.9, the early 7.3s had cavitation issues in the coolant passageways all the way up till 1994. i also woulda done the oil cooler o rings while the motor was out if you didnt. theyre a total pita when the motor is installed
    Last edited: Nov 26, 2011
  5. mnglocker

    mnglocker Senior Member
    Messages: 923

    Cummins 12v Swap.
  6. DJC

    DJC Senior Member
    Messages: 481

    The 6.9 was completely wore out and was going to cost more then it was worth to rebuild. I have the 88 7.3 and I know that it's still good. I'm just not sure how to connect the two harnesses together.