BIGCOOK

I have a 93 xj 4.0 and it Jus started running funny today. It will run and cut off, it won't run for long any idea what it could be?

Bustedback

You have to check for spark and fuel when it dies. No spark could mean a bad crank or cam sensor. No fuel could mean a bad pump or relay.

BIGCOOK

It has spark and fuel but I'm thinking the spark plugs are bad cause it done this one time before but Idk the coil is new but I'll keep checking cause I ain't going anywhere. Stuck on the side of the road

Low Profile

It's unlikely all your plugs would go bad simultaneously. And when one does go bad, it doesn't conk out the whole engine. Usually one plug gets fouled and the engine starts running poorly, missing on one cylinder, poor fuel economy, poor power.

What you are describing sounds like something affecting the entire system, not just one plug. I'm guessing distributor, coil, coil wire, computer, or maybe some kind of fuel supply problem--fuel pump, clogged filter, trash in the tank, etc. The fact that it will run for a little and then stop makes me think it's sucking up available fuel in the line and then something plugs the line, like a clogged up fuel filter. Check your fuel line pressure with the coil wire removed (you don't want some gigantic gasoline explosion in your driveway . . .) to make sure it really is pumping fuel properly.

I had a '53 International truck that suddenly developed an intermittent problem sort of like this and it turned out to be dirt and rust in an in-line fuel filter, from a rusty, crappy old fuel tank.

tjwalker

Did you actually "test" for no spark when the vehicle won't run? Gotta do that. If you are missing spark, the primary suspect is a failing crankshaft position sensor.

Definitely be sure that all tuneup hardware is fresh. Simple stuff first. That means fresh Champion copper plugs gapped to .035, new plug wires, cap and rotor (brass contacts best).

Freshen all engine grounds. Often overlooked.

Don't want to be chasing your tail for something simple.