stumper for you 4.0 techs

My mj recently started acting retarded. I can get it started but after it warms up a bit i.e. go for a short trip, shut it off and try to re-start I get nothing. The starter will turn the engine over but it just won't fire. Here's the odd part...if it happens on a hill I can coast it and get it re-started by popping the clutch. Recently replaced TPS, wries, cap, rotor, plugs, and a few misc vaccum lines. TIA

either battery cables or a bad ground.

replace both the fuel pump relay and ASD relay (auto shut down)

Does it start to spudder before it shuts off? Kinda like a badly tuned carb on a 285 sitting at a 90* angle? If it does do that then it is most likely the CPS.

Maybe the CPS(Crank Position Sensor)

http://www.industryfigure.com/berkeley/Jeep/cps.htm

When I was 16 my VW Bug did the samething. Turned out to be the Coil. When it did it the coil would be very hot to the touch. When it cooled off it would run again.

It also recently started suffering from a power loss...thought it was because i was carrying around a plow. Plow has been off for a while now and I still have to down shift where I never had to before. On the drive to and from work today, I got intermittent hesitation when shifting or really laying into the throttle. This makes me think i have a fuel pressure problem. What should i look at first and how can I test the various parts beyond simply hooking up a pressure gauge.

I´m guessing the 94 still has the fuel filter, up above the drivers side rear wheel well, on the inside frame rail. Over the summer, heard of many mid 90´s XJ´s, with black flecks in the fuel fiter (dump the fuel in a clean jar, blow in the out end). Turned out to be the fuel line, from the pick-up (in the tank) and/or from the tank to the filter, rotting. Worth a look.
Fuel pressure test, will tell you quick if things are plugged up. A refrigeration gauge, will work as a fuel pressure tester, if you don´t have fuel pressure gauge around. I drove, with one tied to my windshield wiper, for almost three days, trying to catch an intermittant problem. Turned out not to be a fuel problem, but an ignition issue.

The next time it happens look for spark at the coil or center distributor cap. Sounds like weak spark and/or a gremlin in the ignition wireing.

And of course the old CPS, symptoms, sound somewhat like a CPS, problem. Next time you don´t get a start, try unpluggeing the CPS and plugging it up again. Have heard this can be benefitial.

this same thing was happening to my XJ a while back. I found that the problem was coming from my nuetral safety switch (NSS). There are a few threads out there talking about it. You just pull it off clean it out and put it back on. Hope this helps
Kevin Bradley

Dont forget the control module in the distributor. When those start to go bad you get no spark after the engine warms up and you shut off and try to restart. Some places can test them too.
marc