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TJ fuel tank/pump/sender swap question


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My fuel tank is shot, and I want it out from under the truck anyway. I have am 87 MJ 2.5L and this is from a 96 TJ 2.5L.

 

I will be building a box in the bed to house the tank.

 

Question is this....

 

What will it take to hook up the TJ fuel pump and sending unit in the 2.5 MJ??

 

Thanks

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The TJ uses an in-tank submerged sender and pump but the float sensor voltage output is the wrong polarity for the MJ fuel gauge. Your gauge will read empty when full and vice-versa.

 

The fix is to pull the fuel sensor out of the TJ tank, and desolder the wire connected to the end of the potentiometer and resolder it to the other end of the potentiometer. This is done on the PC board like in in the pic below.

 

Or you can just live with the wrong polarity readings on the gauge and fill it up when the gauge reads full. :yes:

 

fuelpump-2.jpg

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Another problem with this swap will be that the TJ pump is set up for MPI, and your MJ is TBI. The pressure from the TJ pump will be way too much for the throttle body injector to work properly. At minimum youll need a high pressure fuel pressure regulator to dial back the pressure to TBI specs, either that or rig a TBI pump onto the TJ fuel pump module, which might be more work than its worth. DO your homework. A tank from a 4cyl TBI XJ mounted in the bed might be a better option. Good luck.

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