**please help** trouble with idle and voltage
::CF Moderator::
Joined: Aug 2011
Posts: 43,971
Likes: 1,579
From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
CF Veteran
Joined: Jun 2011
Posts: 2,858
Likes: 1
From: Nor-Cal
Year: 1990
Model: Cherokee
Engine: The venerable 4.0
Originally Posted by cruiser54
Stay focused on that tomorrow. Do you have some good electronics cleaner? I've got another quick project for ya.
Thread Starter
Seasoned Member
Joined: Oct 2011
Posts: 348
Likes: 0
From: Chicago
Year: 1989
Model: Cherokee
Engine: 4.0
Well I fallowed all of those steps and still have some problems, I also changed this part

Vacuum harness (Autozone $53 for both front and back, part numbers 64003 and 64004)
And I am still having idle problems and oil pressure problems, video link attached
https://www.youtube.com/watch?v=FoGT...e_gdata_player

Vacuum harness (Autozone $53 for both front and back, part numbers 64003 and 64004)
And I am still having idle problems and oil pressure problems, video link attached
https://www.youtube.com/watch?v=FoGT...e_gdata_player
::CF Moderator::
Joined: Aug 2011
Posts: 43,971
Likes: 1,579
From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
My next suggestion is to unplug every connector you see in the engine bay, spray it out with the cleaner, then add some dielectric grease and plug it back in.
Thread Starter
Seasoned Member
Joined: Oct 2011
Posts: 348
Likes: 0
From: Chicago
Year: 1989
Model: Cherokee
Engine: 4.0
Originally Posted by cruiser54
My next suggestion is to unplug every connector you see in the engine bay, spray it out with the cleaner, then add some dielectric grease and plug it back in.
Thread Starter
Seasoned Member
Joined: Oct 2011
Posts: 348
Likes: 0
From: Chicago
Year: 1989
Model: Cherokee
Engine: 4.0
Originally Posted by cruiser54
If it's about 3" long and 3/4" wide, with a wire plugged into each end it's your fuel pump ballast resistor. A pic would be good.
Last edited by T85konrad; Dec 9, 2011 at 04:49 AM.
CF Veteran
Joined: Jun 2011
Posts: 2,858
Likes: 1
From: Nor-Cal
Year: 1990
Model: Cherokee
Engine: The venerable 4.0
Fuel pump wiring beat to Hell. You can hook those two wires directly together and see what happens. As cruiser says most if the time these things are ground or wiring/connection problems.
::CF Moderator::
Joined: Aug 2011
Posts: 43,971
Likes: 1,579
From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
Sound advice here. Bypass the ballast resistor and just hook the 2 wires together. The resistor is only there to quiet down the fuel pump.
Thread Starter
Seasoned Member
Joined: Oct 2011
Posts: 348
Likes: 0
From: Chicago
Year: 1989
Model: Cherokee
Engine: 4.0
Originally Posted by cruiser54
Sound advice here. Bypass the ballast resistor and just hook the 2 wires together. The resistor is only there to quiet down the fuel pump.
https://www.youtube.com/watch?v=BbRA...e_gdata_player
I hope its nothing major. I may just buy a whole new wires harness for the engine bay and replace all the wires
::CF Moderator::
Joined: Aug 2011
Posts: 43,971
Likes: 1,579
From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
Get a can of throttle body cleaner and spray all around the intake side of the engine for vacuum leaks. You'll know when you spray one...
As for the wiring, do the "wiggle test". With the engine running, wiggle the harness between the firewall and #1 injector in 6" sections at a time.
As for the wiring, do the "wiggle test". With the engine running, wiggle the harness between the firewall and #1 injector in 6" sections at a time.
Thread Starter
Seasoned Member
Joined: Oct 2011
Posts: 348
Likes: 0
From: Chicago
Year: 1989
Model: Cherokee
Engine: 4.0
Originally Posted by cruiser54
Get a can of throttle body cleaner and spray all around the intake side of the engine for vacuum leaks. You'll know when you spray one...
As for the wiring, do the "wiggle test". With the engine running, wiggle the harness between the firewall and #1 injector in 6" sections at a time.
As for the wiring, do the "wiggle test". With the engine running, wiggle the harness between the firewall and #1 injector in 6" sections at a time.


