would the fuel injection system on an '89 cherokee (fuel rail, injectors, TB, basically everything on the intake mani) work on a '90? i heard a rumor that the ecu was different and the plugs may have had different pin setups because of this.

 

Don't quote me on this because I have never actually been able to get an exact answer myself but, I believe between 89 and 90 was when the big Chrysler buy out happened. I'm pretty sure the 90 model year for the XJ was when the Renix 4.0 was updated to the new 4.0 HO. If that was the case then pretty much everything on the intake manifold going to and including the TB is different. The ECU is completely different as well. My sons 87 4.0 Renix motor and my 91 4.0 HO motor are like apples and oranges. I hope this helps.

 

the HO didnt come out untill '91. right now my xj has a 4.2 in it and im going to be putting a fuel injected set up on it insted of trying to go carbed since all the wiring is still there. and i know the intake mani from a '89 will bolt right up no problem i just need to know the the harness will do the same.

 

The H.O. did come out in 91... the renix parts usually matched in later years so you should be able to interchange up to the chrysler design

 

alright so the whole IM set up from an '89 should have a problem with a '90 wiring harness

 

No, it should not be a problem... biggest difference in the H.O. was bigger injectors and design change on the fuel rail itself... should not affect yours because it is not close enough to the year

 

Harness is the same 87-90 even the part numbers are the same.
BTW if you check the part numbers using a Jeep factory part number you can often find what fits what. I have a parts list on a CD for the Renix years (87-90).

 

alright i appreciate it guys! hopefully i can get the beast running soon!