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Engine hesitates: electrical? fuel?

3,000 miles ago on trip to FL from PA the engine [4.0 6 cyl] began hesitating. At 3 am at 65 mph, I blew burning coals out of my tailpipe. Drove slowly to Jeep dealership at next exit and slept 'til 8.00 am.

No mechanic was on duty but an off duty mechanic hooked me up to the computer and told me it was either the coil or the rotor.

Replaced the muffler & catalytic converter nearby. Drove 300 miles further to friend’s house. We replaced the coil.

Drove to son’s house in Jacksonville. Engine still coughing sporadically. Returned to PA [1,100 miles] still hesitating - wondering whether we’d make it home.

Took car to my local mechanic. He replaced rotor & cap, wires & plugs. No change - still hesitating occasionally.

500 miles ago, my wife got stuck briefly in traffic when Jeep stalled at light. Restarting was difficult [5 min]. Has stalled a half dozen+ times while driving, causing her to pull over and restart.

Took it back to shop. They put an “ignition kit” or something in it. Results were even worse.

While talking to a mechanic from another shop he said he’d probably start by looking at the fuel system. Tonight a fellow from church thought it might be fuel related also.

FYI - bought the Jeep from next door neighbor about 50,000 miles ago. He told me about a peculiarity with the start up procedure. “If it turns over but won’t start, just turn the key off and try again. It will usually start on the 2nd try.” That was 6 years ago and his advice has continued to work; however, sometimes it takes a 3rd try and occasionally a 4th try. [Replaced the battery about 5,000 miles ago.]



Any advice?



My wife loves the Jeep, but would be willing to part with it. We sold our 2002 Mustang to buy the Jeep because we just built a cottage in the woods with a 17% grade gravel road which mandated 4-wheel drive.

I too would suspect the fuel delivery system and start with replacing any fuel filters. There may be more than one, I’m not sure about that. It may be as simple as that to fix the trouble. Have the fuel pressure checked. There may also be trouble with a check valve in the fuel pump that is causing the starting problem when the car hasn’t been running for a while. The fuel may be leaking back into the tank and it needs to be pumped back when first trying to start it up.

The trouble may also be due to a faulty crank sensor. They are a fairly common problem with Jeeps and can cause the kind of trouble you are having.

Try this: Turn the ignition switch on (dash icons lit) and wait for 10 seconds. Turn the key to start and see if the engine runs. If it does it’s probably the anti-drainback valve. The valve keeps fuel pressure on the rail when the engine is off. The crank sensor is also a possibility.

what year how many miles?
flames from the exhaust and replaced the cat and muff? Could be too much fuel in the fuel air mixture when running at highway speed, that will overheat a cat faster than you can say jack rabbit. Is there an 02 sensor on this baby? Was it replaced with the cat?

I too suspect the fuel delivery.

First, the “starting peculiarity” may have been a sign of the fuel system backdraining and losing pressure when the vehicle sat. Two tries at starting would have allowed the system to repressurize.

Second, it sounds like you’re cylinder temps are really hot, a sign of running lean, which can be caused by poor fuel pressure. The stalling and rough running can also be signs of fuel pressure problems.

Yes, very hot cylinders can cause damage to the internal components of the cat converter. While platinum palladium has a melting point of somewhere in the neighbthood of 3000F, the ceramic honeycomb substrate on which it’s deposited can fracture from hot spots.

You’ll want to have the fuel line pressuer and the pressure regulator checked.