did a motor swap and...
Thread Starter
CF Veteran



Joined: Apr 2009
Posts: 18,786
Likes: 14
From: CT.
Year: 88
Model: Comanche (MJ)
Engine: 4.0 HO
I swapped the motor in my 89 xj and now it won't start.
Now this thing ran before I took it apart.
Here's what I found.
No spark
No injector pulse
and no signal to the cps
it has fuel so thats out.
Any ideas?
Now this thing ran before I took it apart.
Here's what I found.
No spark
No injector pulse
and no signal to the cps
it has fuel so thats out.
Any ideas?
CF Veteran
Joined: Jun 2010
Posts: 1,220
Likes: 5
From: Arkansas
Year: 1987 & 1996
Model: Cherokee
Engine: 4.0
http://www.pirate4x4.com/tech/billav...ion_manual.pdf
I would suggest checking the ignition wire on the solenoid by the battery.
Then you can use the ports on the right side firewall to check for power to the ECM.
I would suggest checking the ignition wire on the solenoid by the battery.
Then you can use the ports on the right side firewall to check for power to the ECM.
Thread Starter
CF Veteran



Joined: Apr 2009
Posts: 18,786
Likes: 14
From: CT.
Year: 88
Model: Comanche (MJ)
Engine: 4.0 HO
Thread Starter
CF Veteran



Joined: Apr 2009
Posts: 18,786
Likes: 14
From: CT.
Year: 88
Model: Comanche (MJ)
Engine: 4.0 HO
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Seasoned Member
Joined: Aug 2010
Posts: 298
Likes: 0
From: Galax Virginia
Year: 1996
Model: Cherokee
Engine: 4.0
I know what a headache this can be! I did an engine swap in an old 86 5.0 mustang i had. Got everything bolted and plugged up went to start it and nothing.... Went over everything again and again, changed distributors, swapped in different computers, checked n rechecked connections.... Turns out the car had an aftermarket alarm on it. It had been disconnected before i bought it and i had no knowledge of it. It had a starter kill feature that wouldnt engage the starter. Well when i was hooking things up i reconnected that one wire. Since i never knew of the alarm, had no activation/deactivation buttons it was "armed" and i didnt know it.... long story i know... Car sat for a month no start. Disconnected the alarm wire it fired right up.Good luck to you! Sometimes its the craziest things!
Thread Starter
CF Veteran



Joined: Apr 2009
Posts: 18,786
Likes: 14
From: CT.
Year: 88
Model: Comanche (MJ)
Engine: 4.0 HO
Today after work I'm gonna go over everything again. Yesterday was a long day and I havint had a day off in 2 weeks. Maybe I missed something.
All I know is the computor isint powering up.
All I know is the computor isint powering up.
Junior Member
Joined: Oct 2009
Posts: 92
Likes: 0
From: Orange County, CA
Year: 1993 and 1992
Model: Cherokee
Engine: 4.0L HO(Both)
Just verifying from what you've found- you get fuel, but no spark and no signal from CPS...So it is cranking, just not running. Have you checked for signal TO the CPS? as well as power to the dizzy?
Thread Starter
CF Veteran



Joined: Apr 2009
Posts: 18,786
Likes: 14
From: CT.
Year: 88
Model: Comanche (MJ)
Engine: 4.0 HO
No signal. at all. I'm gonna double check the grounds on the passenger side of the motor after work.


