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fuel pump ballast resistor

99XJLove

NAXJA Forum User
Okay, so I've been doing more searching about my sudden problems with the jeep dying and not wanting to start. It sounds kinda like what people are talking about with the ballast resistor for the fuel pump. I've seen people say that their vehicle just dies and that it won't start for a while then starts back up. Where is this resistor at? If it is the problem I want to take care of it soon.
 
A 1999 4.0 engine doesn't have a ballast resistor. They were used with the Renix engines (up to 1990), and maybe some of the earlier HO engines-not sure about those. What you are describing sounds more like a CPS Crankshaft Position Sensor (11 oclock on the bell housing) going out. There are also several other things that could cause this- they quit working when hot. Ignition module, camshaft sensor, coil come to mind.
 
Okay thanks for the info Bob. I will look into all of those. Can you get to the crank and cam sensors without to much work? Or do you have to tear everything apart? Would either of those have anything to do with the gauges not working when it happened but the dummy lights still lighting up. Maybe the ignition module?
 
Next time it dies, try disconnecting the CPS connector near the throttle body and then reconnecting it. Sometimes this will get the Jeep started.

Or if the Jeep dies when hot, put some ice or water down towards the CPS to cool it off. There are some contacts inside the CPS which will separate when it gets too hot, killing the engine.

Of course, these are just temporary fixes to get you off the street or trail.

The CPS can be a pain to change. It can be done with the right tools and some small hands. Or lowering the tranny also improves the room issue.
 
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btw my 93 ho has a ballast resistor, just fyi
 
I read a couple of TSB's that talk about a wiring connector replacement.
Does your speedo and tach drop out?
Airbag light come on?
My 98 has TSB for removing the dash and cleaning the plug in and then reassemble.
I'd be happy to look up TSB's for your but need what Cherokee you have. When you say it won't start, how bad. try 1 crank let up and then crank again. Does it start better if you do that?
Good luck!
 
What is a TSB? My Cherokee is a 99 4.0L everything on the dash quits except the dummy lights. It's only done it twice and not again yet, it's been a week. I drive it every day. I had just went through an automatic car wash with an undercarrige sprayer. It happend just as I was leaving. I only had like 1/8th of a tank on the gauge. Something like 40 miles on the distance to empty read out. After pulling all of the plugs to the Computer under the hood and drying that out it fired right up.
 
TSB is a Technical Service Bulletin - it's a manufacturer notice to dealership techs advising them of changes or problems in the service procedures.

The lack of dash lights/gauges is one of those, since it is a problem that developed after the vehicle (and service manual) were released.

Jim www.yuccaman.com
 
Go to the dealer with the VIN, and they can tell you the history of work that's ben done and that should be done on it. I don't know if they can print the TSB for you or not though. There used to be some free resources on the 'net that would show you that info as well, but as I understand it those are no longer available.

Perhaps some of our members/users who have access can copy the info?

Jim www.yuccaman.com
 
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