97+ conversion question

[jeff351]

I might have missed it somewhere, so I apologize if its been asked before. 

 

What is the reason you all are swapping out the fuel tank for a different one when doing this conversion?

[gogmorgo]

If you're talking engine conversion, the '97+ system has a returnless fuel system, so the fuel pressure regulator is built into the fuel sending unit. The later sending unit also drops in from the top of the fuel tank, not from the side like the early ones, so it's easier to swap out to a tank and sending unit that are compatible with the system than to adapt the later sending unit into the MJ's factory tank.

If you're only swapping the front end for the later look, there's no need at all to swap fuel tanks. Only if you're also converting the interior and want the dash to work correctly.

[AZJeff]

"Gogmorgo" is correct.   The 97+ engine control system has the returnees fuel system.  Also, the wiring harness/ECU for those engines also is connected to the instrument cluster.  This means that, to get everything to work as expected, one has to

 

1.  change the wiring harness to match the engine

2. change the instrument cluster/dashboard to match the wiring harness

3. change the fuel gauge to match the instrument cluster

4. change the fuel tank to match the fuel guage

 

When all of those are done together, you essentially have the instruments and engine controls of a 97+ XJ in your Comanche.   (It's what I have.)

[cruiser54]

An afternoon job then.