93 Jeep Grand Cherokee, stupidautomatic transmission, inline six, full-time 4x4.

The wife drove it home and shut it off.

A couple hours later, she jumped in it and it would crank over, but no start.

She tried it again, a few hours later.

The next morning, I tried it, no start; then, I checked what few silly little things that I could, with my feeble knowledge, and still no start.

I couldn't hear if the fuel pump was running, for all the stupid little bells and buzzers going off; as soon as I get time to get under the dash, no more bells and buzzers will be heard.

It would whirl over with ease, but no start.

Then, tonight, she goes out there and the dumb thing starts the first turn-over.

We tried it a few more times, about half an hour apart, and it started easily each time.

What are the suspected causes for this; and, is it going to get her out somewhere and not start, again??

Thanks.

 

Was it raining or did she drive thru water just before shutting it down?

 

One of the most important things to check when there is a no-start on an EFI 4.0 litre in a Jeep is the crank sensor - it is a very common failure that will cause a no start. If you don't have a code reader, pop one of the injector harness connectors off of an injector and take an automotive peanut bulb and bend the two wires down so that it will fit into the connector. While observing the bulb, crank it over and watch for it to pulse....if it doesn't, you most likely don't have a crank signal to the ECM, therefore, no fuel or spark. Of course, all this can be confirmed with a code reader.

 

Definately ....crank Sensor

 

Again, this morning, damp and foggy, crank and crank, but no start.

I am beginning to believe it is dampness related.

Thanks.

 

Moisture can affect the CKP if the body of it is cracked.....

Do the peanut bulb test if you don't have a code reader when the problem persists.

 

Where is this CRANK SENSOR located; and, how do I identify it??

The dumb thing only fails to start when early in the morning and I don't have time to fool with it; then, in the evening, when I get home, it will start the first turn of the engine.

It has failed to start every morning, since this problem surfaced.

I will run the bulb test, as soon as I get a chance to, while it is still early enough for it to present it's problem.

Thanks.

 

Crank sensor is in the bellhousing...on the top but toward the drivers side. Kinda tough to see/get to, but it's there. Like others have said, you're experiencing classic crank sensor problems. Sometimes it'll go for weeks with no problems, then not start for days on end...it's just more fussy chrysler electronics

 

This is beginning to sound like something to take to the local mechanic, rather than me spend a day, cussing and crying, and it still not be fixed.

How big a chore is this gonna be, laying on my back, on a gravel drive-way??

Thanks.

 

Sounds a lot like what mine did and it was crank sensor , real nice spot to get at . The fuel pump is another weak area on the 4.9 , in tank . Other than that they run a long , long time . Mine is close to 300,000 and other then crank sensor , fuel pump , belts and brakes it has been great .

 

next time it doesn't start, kick the fuel tank a few times with force and try again. If it starts your pump is on its way out...

 

I've done a few crank sensors. Some out in the field, on my back in the rain, I guess that's why they pay me the big bucks . Anyway, its not a very difficult job, just be patient in getting the wrench to it. But I am a big believer in confirming whats wrong, before changing parts till the problem goes away.