motor cuts out while driving

within the past week or two my 99 xj (almost 140k) has been shutting off on me while im driving, although it doesnt sputter or anything just dies. the first couple of times i was able to fire it right back up and keep driving but now it wont. the first time it wouldnt restart i had jumpers on it and left them there for about 15 mins, and it started up after that. the second and most recent time i had to let it sit over night and then it started up the next day without problems. after it dies if u turn the key it cranks but wont fire. within the past year ive had the fuel pump replaced and after this started happening i replaced the battery and the spark plugs and wires. not sure where to look next for solving the issue...

i was out driving it again today and my oil pressure is higher then normal right now and also had a noise that sounded like a cricket while stopped at stop signs...

Begin with basic trouble shooting of the start and charge systems. Remove, clean, and firmly reconnect all the wires and cables to the battery, starter, and alternator. Look for corroded or damaged cables or connectors and replace as needed. Do the same for the grounding wires from the starter to engine block, and from the battery and engine to the Jeep's frame/body. Jeeps do not tolerate low voltage or poor grounds.

Make sure the fan belt is tight.

Have the alternator and the battery tested.

If you do all of the above and still have the problem, replace the CranKshaft Position Sensor (CPS/CKP)

also, check fuel pressure at the rail and check the fuel pump relay. try to prime the engine first buy turning the key to on and off 4 or 5 times, then try to start. I know you said you replaced the Fuel pump last year but check anyways.

Another thing you could look for is, there is a radiator "half moon shaped retainer" by the battery terminals. Make sure that it's not bent towards your battery, if it's been touching you'll have "witness" marks. I know it sounds far fetched but it happened to me and would cut power. Just an option incase you're running out of ideas.

Tim_MN said:

If you do all of the above and still have the problem, replace the CranKshaft Position Sensor (CPS/CKP)

Click to expand...

My money is on a flaky crankshaft position sensor. IMHO, it may be the most common sensor failure on the Jeep 4.0

If you do replace it, I recommend buying it from Jeep for best reliability. Aftermarket crank sensors (some, not all) are not built that well.

thanks for the help.... replaced the CPS today, gunna drive it tomorrow to hopefully have it fixed. have to replace the alternator too cuz it on its way out... after that it should be good to go for awhile.