I have a 1995 jeep cherokee 4.0 that runs fine for about an hour are an hour and half then will suddenly shutoff....turn off switch and restart can hear the fuel pump buzz it will start and go about a half a block are so then die again....let it cool off about thirty minutesand it will run fine for about another hour then same thing....have changed crankshaft position sensor...new ecm...new ignition switch...new module in distributor...new battery cables....was getting a code 42...asd shutdown....what triggers this code?...cleared codes and now i am getting a code 54...module in dist which has already been replaced.....three different shops cannot solve problem....any help would be greatly appreciated...i use this vehicle to do my job...am a rural mail carrier and these vehicles are perfect for my job...dont want to let it go...

 

Did you try replacing the buzzing fuel pump? What temperature is it running?

 

No...what i mean by buzzing is the normal sound it has always made when u first turn the key on....temp is about 205 to 210....but i do hear the electric fan cycling when it happens...

 

I had similar problems with a 78 ford bronco. The problem was the distributor. We replaced it and no problems since.

 

http://www.angelfire.com/empire/auto...ble_Codes.html shows the codes. They both seem to indicate circuits/voltages. I would check the actual wiring, it runs when cool but dies when hot so maybe the wires themselves are the cuplrit? Heat increases resistance.

 

Fuel injectors??? When hot they are failing?? I had similar issues, replaced injectors and all is good.

 

for some reason it sounds electrical to me... maybe a bad ground somewhere? Bad ground/connection on the alternator?

 

im thinking coil

 

this

 

I agree with the electrical thing. I would check the coil too. As stated. Check tghe wirring. Make sure its not briddle and is not near anything hot enough to melt it. Make sure u check the coil and module for ohms resitance. Did u change the cap and rotor? If so did u use dialectric grease on the brass conductors?

This whole area stated above is where I would want to be 100% sure is good.

 

Checking the resistances of the coil probably will test good even if it's bad. It's a dielectric breakdown internally - an Ohmmeter won't find it.
They aren't expensive - try replacing it. Avoid the "trick" coils claiming better performance, none are as good as stock!

A problem area - easy to try it - symptoms say crankshaft position sensor - but it's new. BUT the connector may be suspect - it's right under where the body and hood meet - any drips get it wet. Sometimes they corrode inside - it's a very weak signal - any corrosion cuts down on the signal. As it gets hot, connection is lost.
Simply open the connector - clean it good with contact cleaner, then coat with dielectric grease. Many CPS's are changed when that was actually the problem.

 

That's a great point. I had a bad coil on a trans am I had and it tested good via an ohm meter. But I was at the end of my trouble shooting rope. So I replaced it and it worked. Also the cps wirring is another excellent point. Pay close attention to that.

 

There were a few years in the early to mid 90s, like yours, that Jeep had a failing coil issue even when new. One vendor in particular supplied the bad coils.

 

Have you ruled out the possibility that the Crankshaft Position Sensor you picked up was faulty? I have heard many cases of them being bad right from the box.

 

When it doesn't restart have you checked to see if you are getting spark, or fuel. You need to narrow it done to what system is not working before you replace anything. Take a screw driver and a can of braek clean with you and the next time it dies spray the brake clean into the intake tube at the air filter. if it tries to start its a fuel problem. If that doesn't work take the coil wire off at the cap and stick the screw driver into the end and rest it against something metal and crank the engine. If you see a nice blue spark the coil is working, now do the same thing to #1 cylinder wire. .02