ive got a 94 yj 4cl had some major issues this winter fixed all that with new cpm but now you drive down the road and acts like its running out of fuel "spits and stupders" and just die i can get out and poke the valve on fuel rail fuel spays out"pretty dumd thing to do on hot motor" then wont start for awhile then fires up and goes maybee 2 miles or maybee 200 miles before it does it again any help would be nice
the parts ive changed pre cpu change cpu,plugs,cap and button,coil,cps after cpu fuel filter and check fuel pressure "was good according to chiltons book"
so like i said any help would be nice <img src="/forums/images/graemlins/confused.gif" alt="" />

Start by replacing the fuel filter.

already tryed that

Have you checked for engine codes?

Have you replaced the knock sensor?
An over active knock sensor might be forcing the timing retarded.

Did it run Ok for a while after you replaced it? Might have reclogged if so.
Big Jim <img src="/forums/images/graemlins/pfft.gif" alt="" />

big jim i dont want to sound dumb but dont know what the knock senor is and where its at <img src="/forums/images/graemlins/confused.gif" alt="" />

The knock sensor monitors the engine for detonation. It is like a microphone that vibrated at a certain frequency sends out AC voltage. It is set at the frequency the whole engine vibrates at when the fuel doesn't burn right. Every once in a while they will go bad, sending out the AC voltage if the engine is running fine or not. When ever the computer gets a signal from the knock sensor, it pulls the timing retarded in order to bring it back under control. If the knock sensor is always putting out the AC signal, the computer will drive the timing to a point that the car won't run. It's a long shot, but since you have replaced a lot of things it may have been over looked.

I've heard of this knock sensor, but never dealt with one....

Could this also be the carbon canister causing too much vacuum on the tank? Try popping your gas filler cap when she is misbehaving and see if a quick rev will make it behave. It tends to work on some older YJ's all the time... Give it a shot....

I had a similar issue on my cherokee recently and I found that the screen attached to the fuel pump had fallen off and was floating around in the tank. I guess it was occasionally blocking the pick up? I pulled the pump, because I had replaced it not too long ago and I figured I got a bad one. As it turned out I shouldnt have re-used that screen. After replacing the screen with a new one, the problem has gone away. Good Luck.