It spits and sputters and some times hard to start

i would start by replacing the fuel filter.

If you have not replaced plugs start there A bad map sensor will also cause black smoke and poor running

GO TO KNECHTS AUTO PARTS , HAVE THEM CHECK THE CODES ON THE COMPUTOR THEN GO FROM THERE !!

Have the shop check fuel pressure at the fuel rail. Maybe the pump impeller has failed. If fuel pressure is good, your timing chain/belt may have slipped.

I assume you are talking about the timing belt? Your answer is it depends on how far off the timing belt is, if it is way off you may not even get a spit or a sputter. If its a tooth or so off it should still run poorly.

I have the same problem on my 95 grand cherokee laredo. Sometimes it starts out fine and after about 10 miles it starts spitting and sputtering. Then after a while it seems to clean out and run fine again for a little while. Then other times it starts out spitting and sputtering at the begining. I changed the fuel filter and that was not it. It is a 4.0L 6cyc. Any Ideas?

Thanks,
Broken Arrow, OK

when the last time u did a tune up?

My brothers 97 silverado did the same thing. He replaced the fuel pump and the problem stopped.

if you have an electric fuel pump that would explain the hum. unhook your incoming fuel line and blow the line clear, sounds like you've got some junk in your tank.it'll build up on the screen in the tank then fall off (at least partially) when your making turns or hitting bumps or holes. next time it's only got a gallon or so of fuel i'd drop the tank and check the pickup tube inside. sux but that's the only way to get to it. while you've got the tank off and out from under the jeep, might as well clean it out real good and replace anything inside (usually the screen) that doesn't look right, dirty etc. wouldn't hurt to run a bottle of fuel system cleaner in the next full tank of fuel either. preferably as soon as you put your tank back. good luck

Have you checked you timing the belt might need to be changed.