Jeep Cherokee problems... any ideas?

[Caliber357]

I recently got a 1990 Jeep Cherokee Laredo in a trade for a few guns, and it needs quite a bit of work done on it. Most of it's fairly straight-forward stuff, but I've got one major problem I can't figure out. It cranks for about 5-6 seconds before starting, and the engine runs weak especially at idle. I replaced the spark plugs, wires, distributor cap and rotor, and it still does it. Not a big deal, it drives fine once it's on the road. But, frequently (and I mean like twice per trip down to the local gas station) the engine just completely dies. I can't rev it with the gas petal, the power steering cuts out, and the brake petal is much less responsive. I can turn on the headlights and radio, and battery shows that the charge is ok, but the engine's just kaput. If I let it sit for a few minutes I can eventually get it to start again, but it cranks for almost 20 seconds before it sputters to life. A friend of mine says that's probably a fuel pump - does that sound right to you guys? This happens completely randomly - doesn't have anything to do with speed, RPM, hills, flat ground, anything.

[XJ]

Fuel pump will likely make noise before quitting on you, if the filter is clogged it is not much fun getting the pump out of the tank.

It also be that the various sensors are unhappy, check the throttle body to see how much gunk is there.

Before getting in depth, I am assuming this is the 4.0L but it never hurts to ask.

www.naxja.org is the absolute best cherokee website anywere, and their tech forums have a wealth of information. plenty of CO folks are active there too.

[7idl]

I too say fuel filter(s)

might want to make sure (since this is "new" to you) to change all the filters. PCV, Air, Oil, Fuel.

[HunterCO]

Could very well be a fuel pump they do not always make noise before they quit and sometimes they can be very random in the way they act.

If I could diagnose your vehicle over the internet I would sell my shop open a web site and make millions. There is no way anybody can say with out diagnosing the problem. You are welcome to hit all the websites with all the experts who will cost you twice as much as what it will cost you to take it to a real expert.

[7idl]

this is probably a good time to plug our very own HunterCO...

He's the auto mechanic to the stars (us)

He's the real deal. Don't be affraid to bring your work to him to get it fixed right.

[Atrain]

Hunter's right, it could be a million things. Take it to him and let him check the fuel pressure. If you are determined to hunt the problem down on your own, the hard starting, crappy idle, stalling, but running fine once you are up to speed makes me suspect the Idle Air Control valve...it's a small part on your throttle body and very easy to change out. Good luck!

[XJ]

But you still need to tell us if it is the 4.0 six or the four-cylinder.

If the latter, I hope you traded no more than a Lorcin for it

[Great-Kazoo]

O2 sensor or catalytic converter as last resort. fuel pump and or the pickup in the fuel tank. what color is the tail pipe? darker/sooty leads to an O2 sensor which gives you crappy gas mileage, hard starting, sluggish (to say the least) off the line.
BUT
the least expensive way to trouble shoot any mechanical (retired wrench here) is to pay a professional to run a comp code scan for you. pay the diagonisis fee and go from there.
you'd be surprised how much you save vs. replacing anything you think might be the cause.