I bought a 93 xj that has a 4.0 liter out of an 89 xj. The guy we bought it from did the engine transplant. He says it will not start. getting fuel just no fire. I am fairly new to jeeps so I was wondering if there is any difference in wiring and computers from 89 to 93.

 

89 was a renix 4.0, the 93 is an HO. the computers and wiring are different. has he had it running at all since the swap? perhaps he didn't complete it correctly

 

Flexplate possibly different and could keep crank sensor from operating.

 

I went and got the jeep today, tried computer and coil pack out of my own, no start. the wiring looks the same, I haven't found any missing conectors or sensors not plugged in. I am going to get the computer for this engine and try it,I have juice to the dist. but no fire to the plugs. Iam wondering if the cps could be the whole problem, Doesn't the cps tell the coil to fire?

 

No it tells the computer when to let the injectors have their power to inject. IIRC

 

so even if the cps is not working, I should still have fire to the plugs? Because i have zero fire to the plugs, but I can smell gas in the throttle body plenum. More than likely it will be the computer.

 

is there a way to check if the cps is bad or not ( ex. ohm meter, test light). I have the original engine, could I change everything over to the new engine and make it work?

 

did you check the cap and rotor to make sue they were good or even there?
If you have spark at the distributor the only reason why you would not have spark at the plug is the wires. the wires are the only thin between the dist. and the plugs.

 

Back to the CPS. The CPS from a Renix needs the Renix flexplate to give it's signal to the computer. Same the other way around H.O. CPS needs H.O. flexplate to work. They have to match each other.