HO 4.0 Swap into 87 YJ - Pirate4x4.Com : 4x4 and Off-Road Forum

monstertruckin · 02-18-2005, 10:57 PM

I bought an 87 Yj a couple nights with the factory drivetrain. I've got a complete drivetrain out of a 91 XJ, including the wire harness. What does it take to make that motor work in my carbed Yj? Is there a tech writeup or anything that you know about where I can read about this. I don't have the donor XJ anymore, as I needed to get rid of it. When I pulled the drivetrain, I didn't have plans of using it myself. Wish I'd still have it laying around here, because then I could probably get it to work pretty easily.

grljeeper · 02-19-2005, 09:06 AM

Take a look at CJoffroad there is a ton of information. Then it's just a matter of your threshhold of pain.

Avanteone · 02-19-2005, 09:07 AM

I just recently completed this swap into a buddie's YJ with an XJ 4.0. First off, you have to used the motor mount brackets, the part that bolts to the motor, off of the YJ. The xj brackets will work and let you install the motor, but it offsets it too far to the drivers side. The wiring wasn't TOO hard once we sat down and figured out the wiring diagrams. We took the engine compartment side of the YJ wiring harness and cut off the connector with about a foot of wires remaining. Be sure only to cut the ENGINE side of the connector, not the body/lighting side. We sat down with both wiring diagrams and started matching up wires. For instance, found the orange wire for the blower motor coming out of the YJ bulkhead connector and connected it to the appropriate wire in the XJ harness. Then found ignition feed, etc. It really ended up being MUCh easier than we thought. For the fuel pump, the his '89 YJ was already wired up for power, they must do that because the 4cyl's are fuel injected, even though his was a 258", they pre-wire it. So we simply mounted the xj fuel pump into the YJ sender assembly, it worked perfectly. The wiring is the hardest part, but if you sit down with both wiring diagrams it really isn't too bad. We mounted the computer in the same place as the original YJ and the grommet for the wiring harness is even the same size. I hope this answers some of your questions. He was VERY happy with the end result of the swap. Feel free to email at Avanteone@aol.com if you've got more.

John

monstertruckin · 02-20-2005, 02:08 PM

Thanks a lot for the feedback. I think I'm gonna give this a shot. I've got the 91 4.0, auto tranny, and tcase all out of the xj. I threw away both of my xj's already, which I'm now regretting. I think I can go back to the boneyard and get some parts off of one of my xj's though, because I saw it sitting there a couple days ago still. I may end up emailing you though, if I run into any problems. It all sounds pretty straight forward. I just need to find the time to sit down in the shop and figure it all out. If it's not alcohol injected or blown, I really don't know what I'm looking at :-)

02-18-2005, 10:57 PM	#1 (permalink)
monstertruckin Registered User Join Date: Feb 2005 Member # 42705 Location: New Jersey - Minnesota Posts: 11	HO 4.0 Swap into 87 YJ I bought an 87 Yj a couple nights with the factory drivetrain. I've got a complete drivetrain out of a 91 XJ, including the wire harness. What does it take to make that motor work in my carbed Yj? Is there a tech writeup or anything that you know about where I can read about this. I don't have the donor XJ anymore, as I needed to get rid of it. When I pulled the drivetrain, I didn't have plans of using it myself. Wish I'd still have it laying around here, because then I could probably get it to work pretty easily.

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02-19-2005, 09:06 AM	#2 (permalink)
grljeeper Registered User Join Date: Dec 2002 Member # 15668 Location: Fresno, cA Posts: 429	Take a look at CJoffroad there is a ton of information. Then it's just a matter of your threshhold of pain.

02-19-2005, 09:07 AM	#3 (permalink)
Avanteone Registered User Join Date: Jul 2001 Member # 5632 Location: Auburn, WA Posts: 209	I just recently completed this swap into a buddie's YJ with an XJ 4.0. First off, you have to used the motor mount brackets, the part that bolts to the motor, off of the YJ. The xj brackets will work and let you install the motor, but it offsets it too far to the drivers side. The wiring wasn't TOO hard once we sat down and figured out the wiring diagrams. We took the engine compartment side of the YJ wiring harness and cut off the connector with about a foot of wires remaining. Be sure only to cut the ENGINE side of the connector, not the body/lighting side. We sat down with both wiring diagrams and started matching up wires. For instance, found the orange wire for the blower motor coming out of the YJ bulkhead connector and connected it to the appropriate wire in the XJ harness. Then found ignition feed, etc. It really ended up being MUCh easier than we thought. For the fuel pump, the his '89 YJ was already wired up for power, they must do that because the 4cyl's are fuel injected, even though his was a 258", they pre-wire it. So we simply mounted the xj fuel pump into the YJ sender assembly, it worked perfectly. The wiring is the hardest part, but if you sit down with both wiring diagrams it really isn't too bad. We mounted the computer in the same place as the original YJ and the grommet for the wiring harness is even the same size. I hope this answers some of your questions. He was VERY happy with the end result of the swap. Feel free to email at Avanteone@aol.com if you've got more. John

02-20-2005, 02:08 PM	#4 (permalink)
monstertruckin Registered User Join Date: Feb 2005 Member # 42705 Location: New Jersey - Minnesota Posts: 11	Thanks a lot for the feedback. I think I'm gonna give this a shot. I've got the 91 4.0, auto tranny, and tcase all out of the xj. I threw away both of my xj's already, which I'm now regretting. I think I can go back to the boneyard and get some parts off of one of my xj's though, because I saw it sitting there a couple days ago still. I may end up emailing you though, if I run into any problems. It all sounds pretty straight forward. I just need to find the time to sit down in the shop and figure it all out. If it's not alcohol injected or blown, I really don't know what I'm looking at :-)