1990 comanche no spark
#1
Junior Member
Thread Starter
Join Date: Nov 2014
Location: Kalispell, MT
Posts: 37
Likes: 0
Received 0 Likes
on
0 Posts
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0L
1990 comanche no spark
i have spent the last three days reading a bunch of forums trying to figure this out. i have a 1990 comanche 4.0 5 speed. i went to the store the other day and when i came out the jeep wouldn't start. got it home and the first thing i did was replaced the cps with a new one. when that didn't work i changed the coil with a known good one, still no luck. then i cleaned every ground on the motor, still nothing. finally i decided to swap in a different ecu and finally the jeep decided to run, i drove it around for a hour or so and came home. when i went to leave the same thing happened no spark. i'm getting pretty frustrated and would really like to get this jeep back on the road. any advice is appreciated. thanks
#2
CF Veteran
Join Date: Oct 2013
Location: Miami, fl
Posts: 7,378
Likes: 0
Received 2 Likes
on
2 Posts
Year: 1998
Model: Cherokee
Engine: 4.0
So it's crankIng and no spark?
Might be fuel...double check the ground behind the left tail light and switch around the relays to see if you have an malfunctioning one...
Might be fuel...double check the ground behind the left tail light and switch around the relays to see if you have an malfunctioning one...
#3
::CF Moderator::
Join Date: Aug 2011
Location: Prescott, Az
Posts: 43,864
Received 1,524 Likes
on
1,236 Posts
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
Testing things would be good.
+1000 on the taillight ground.
Ever been to www.cruiser54.com?
do Tips 1,3,4, and 5 for sure.
+1000 on the taillight ground.
Ever been to www.cruiser54.com?
do Tips 1,3,4, and 5 for sure.
#4
CF Veteran
Join Date: Feb 2012
Location: college station
Posts: 1,116
Likes: 0
Received 0 Likes
on
0 Posts
Year: 1988
Model: Comanche
Engine: 4.0
Just cause you replaced the CPS it doesn't mean its good. Alot of the Cps from the local parts store are poor quality and have a large failure rate right out of the box. I would do cruisers tip on testing it to make sure its putting out the right parameters before you spend any more money on parts. for sensors you should always go OEM.....
#5
Junior Member
Thread Starter
Join Date: Nov 2014
Location: Kalispell, MT
Posts: 37
Likes: 0
Received 0 Likes
on
0 Posts
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0L
i've done tips 1,3,4, and 5 also tested the cps and got a reading of .3 ac volts.
Testing things would be good.
+1000 on the taillight ground.
Ever been to www.cruiser54.com?
do Tips 1,3,4, and 5 for sure.
+1000 on the taillight ground.
Ever been to www.cruiser54.com?
do Tips 1,3,4, and 5 for sure.
#6
::CF Moderator::
Join Date: Aug 2011
Location: Prescott, Az
Posts: 43,864
Received 1,524 Likes
on
1,236 Posts
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
.3 is low.
Look around the area where the CPS plugs in. See an identical plug with same colored wires but not plugged in?
Look around the area where the CPS plugs in. See an identical plug with same colored wires but not plugged in?
#7
Junior Member
Thread Starter
Join Date: Nov 2014
Location: Kalispell, MT
Posts: 37
Likes: 0
Received 0 Likes
on
0 Posts
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0L
Trending Topics
#9
::CF Moderator::
Join Date: Aug 2011
Location: Prescott, Az
Posts: 43,864
Received 1,524 Likes
on
1,236 Posts
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
The factory had a service bulletin to replace the harness between the CPS and eCU. Part of the instructions stated that the old connector should be removed. some techs didn't do that...
Hence, some poor sap like you or me plugs a new cPS into dead harness.
#10
Junior Member
Thread Starter
Join Date: Nov 2014
Location: Kalispell, MT
Posts: 37
Likes: 0
Received 0 Likes
on
0 Posts
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0L
took apart two of the ecu's and this is what i found on both. something is shorting it out. not sure what but i definitely do not want to burn up another one.
#11
::CF Moderator::
Join Date: Aug 2011
Location: Prescott, Az
Posts: 43,864
Received 1,524 Likes
on
1,236 Posts
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
Can you trace that to a pin on the ECU?
I have a pin-out for it.
I have a pin-out for it.
#12
Junior Member
Thread Starter
Join Date: Nov 2014
Location: Kalispell, MT
Posts: 37
Likes: 0
Received 0 Likes
on
0 Posts
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0L
#13
::CF Moderator::
Join Date: Aug 2011
Location: Prescott, Az
Posts: 43,864
Received 1,524 Likes
on
1,236 Posts
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
#14
::CF Moderator::
Join Date: Aug 2011
Location: Prescott, Az
Posts: 43,864
Received 1,524 Likes
on
1,236 Posts
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
Take a look where the injector harness transitions from the front of the intake manifold down to the CTS, knock sensor and 02 sensor.
#15
Junior Member
Thread Starter
Join Date: Nov 2014
Location: Kalispell, MT
Posts: 37
Likes: 0
Received 0 Likes
on
0 Posts
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0L
i disconnected everything down there and pulled the harness up. took back the sheathing around the wiring and inspected them up to where they meet the injectors and did not see anything wrong. other then the knock sensor wiring has three wires and one of them was completely bare the whole way.