Was cruising today when my Cherokee just shut down at 50 MPH. Now all it does is turn the engine over freely. I have checked for a spark at plugs which I have none. Replaced coil and dist.pick up but no change. Any ideals on whats next to check?

 

Crank Position Sensor?

 

Have not checked this, not sure of the location of it. Thought maybe it might be the module on the driver side fender weld but have no way to have it test. Cost $300 at parts stores. Could be an expensive guess

 

How freely? Is it turning over faster now than previously?

 

is the engine running? could be the fuel pump

 

Yes, it seems to be turning over easier, kinda like when you pull the plugs. When you turn the ignition on fuel starts pumping through the gas line.

 

Broken timing chain?

They have an electric fuel pump, so if its working, it will pump fuel with the key on.

 

I'd start with tests & numbers. Test fuel pressure at the rail, then do a compression test. Then go from there.

 

1st thing check codes with key on off thing. Crank sensor is where motor & tranny mount on drivers side, up high by firewall. Definitely get mopar if you buy any sensor. Could be ecm. Fuel pressure could be checked with gauge on fuel rail(I doubt this is cause though). Check ignition wires, coil wire, coil. Ignition fuse?

 

That is a good suggestion! Had not thought of that possiblity. Was fixed on the fact of no spark.

 

Fuel Pressure is good. Have checked the dist. cap, plugs and plug wires. Have installed new coil and dist.pick-up. Still no fire.

 

All fuses are good.

 

My original fear was the ECM. I can get one from the salvage yard for $75, just hate to spend that if it is not the problem. My wife bought this vehicle new and it has gone through her, my daughter and two sons. It has 135000 miles on it and has never broken down so we can't complain. I bought it from my son before he deployed to Iraq in Dec. to keep it in the family.

 

run a hot wire to your coil and see if it will fire. if it will, trace it backwards until it won't. i had an old cj that did the same thing to me. it would lose spark driving down the highway and die. i thought i fixed it several times. in the end i ran a hot wire to the coil through a toggle switch on the dash. that fixed it for good.

 

Good for anti-theft, too.