HO 4.0 swap, having problems

[Keats]

I swapped a HO engine out of a 92 comanche into my 89. I moved the entire wiring harness into my truck, inside and out. Got it all set up to start, and have nothing. No spark, fuel pump, or ignition.

 

The motor will turn over if you jump the starter.

 

The fuel pump will kick in in you jump over the relay in the PDC.

 

There is no spark, and I can't get it to spark.

 

Idea's??

[Pete M]

Did you swap in the newer CPS?

[JOMJ87]

You may have ignition problems. For example if you ignition control wires run thru a junction on you truck the new harness may have the wires in diff locations ion the junction block thus them not getting power to them or working. Maybe try jumping all the ignition control stuff straight to your key or a switch or something. My buddy had to bypass the junction block on his when he done this swap in his YJ. I think i have an article on it i will dig and see if i can find it.

 

Cole

[Eagle]

I think Pete's on the right track. You didn't say what you did about transmissions and bell housings, but the flywheel and CPS for the 91+ Chrysler engines is totally incompatible with the flywheel and CPS for the 87-90 Renix system.

[LEAD_NOT_FOLLOW]

I think Pete's on the right track. You didn't say what you did about transmissions and bell housings, but the flywheel and CPS for the 91+ Chrysler engines is totally incompatible with the flywheel and CPS for the 87-90 Renix system.

Correct.

 

You need to use the HO CPS as well as the HO flexplate/flywheel. Once that is done it should fire right up.

 

(delt with this exact issue last week with a buddy)

[Keats]

Pete, Eagle, and Lead-

For once,I actually did my research on this forum prior to doing the swap, and thanks to guys like you, I already did the flywheel/CPS swap. :cheers:

Sorry I forgot to include last months tranny swap in the description,It's now an AX-15 (with internal slave), instead of the puke.

 

JOM,

That was actually the next thing on the list to try. Just seems like the easy way out, since that doesn't help the fuel pump or starter, and I don't really want to have all the switches/buttons to run everything seperate.

 

Seeing as I'm not gonna be able to wrench much tomorrow, I thought I'd see if I could find the right way to fix it, instead of starting to cobble a bunch of toggles to get this thing to run....(Which is exactly what would happen, I'm stumped.)

 

Thanks for the help, anymore ideas?

[JOMJ87]

OH yeah i forgot the fuel pump wires on his YJ didnt match up for sure. One was suposed to be ran to a hot but at the junction it was on a ground wire. Just some more stuff to check. These thing can big headaches i know cause I'm getting ready to do it with his old 2.5 but i can't pass up a motor with only 37000 miles on it for as cheap as i got it. Good luck and if you have any questions i can get pics of his and a good explanation for you. BTW he just bypassed the junction block and ran it to the ignition so it still looks stock and function like it is. Its a little tighter to do on a MJ cause theres so mutch junk under the dash but its feasible.

 

Cole

[MiNi Beast]

I had same problem but switch out all wiring. The dash wiring and cab wiring all the way back to taillights. Under the dash I jumped the fuel pump to the ignation, so fuel pump comes on with the key on. Then the starter I ran to toggle switch. So everything works like noral but starts on toggle switch, like a push botton start conversion. Found that it dosen't take as long to start like the 4.0 seemily is. Just idea.