Jeep Died / No Start

Alright, I am stumped and unsure of which direction to go.

96 XJ 4.0L Auto

Jeep died while idling and wouldn't restart. It cranks but won't start. There is fuel at the fuel rail and the fuel pump is working. There is no spark as far as I can tell. Jeep is not throwing a code. First thought was CPS. I replaced it with still no start. My other thought was cam position sensor but I am pretty sure it wouldn't crank if that were bad. Battery is fully charged (on a float charger). What should I check next?

I would perform a couple of quick and dirty tests to verify what part of the starting equation you are missing, spark or fuel or both. Once you know that, the suspect list gets a whole lot shorter.

How did you determine there is no spark? Pull a plug, keep it attached to the wire, place the electrode near a good engine ground. Have a buddy crank the engine while you watch. You're looking for a strong, blue, snapping spark. Orange indicates weak spark which isn't good.

Another thing you can try is to spray a shot of starting fluid into the intake. If the engine starts and runs momentarily, you have a fuel delivery problem. Just because you hear the fuel pump run and have fuel pressure at the rail, doesn't mean that the fuel is actually making it to the injectors.

Good luck and let us know what you find!

Mine did the same thing last week and come to find out it was my injectors. I don't know why it worked for me but rotate all your injectors and couple of times and try to fire it up. Might help for some odd reason it worked for me and everytime mine didn't start that was the first thing I did. Worth a shot!!!

It WOULD still crank, even without the cam pos sensor. Like birch said, you need to know for sure if you have good spark or not. You need to pull a spark plug anyway to see if they are fouled out or too old.

I pulled the plugs, they are not fouled and and it had no spark.

Check ALL your fuses, under the dash, and in the PDC on the passenger fender under the hood. I just went through this with my '96 and it turned out to be a hidden short in the O2 sensor harness. If you have a blown fuse, that can lead you to the problem. Check the fuses with a volt meter/continuity tester...sometimes they look OK, but wont pass a cont. check.

Steve

Did you get something wet lately?

I'd wiggle all the wires, coil, the harness to the distributor.

Did you ground the spark plug to the block or did you just hold it while you cranked? I've done that before and with no ground, there's no spark.

I've had two phantom no start issues solved by a fuel filter. How long has it been since you've replaced it? Never? I'd bleed all the pressure at the rail, then turn the key a few times and make sure you've got fuel pressure up there.

Ignition coil?

Ignition control module? Thats what caused Andy's rig to do the same thing. Its the little base that the coil fits into.

Ok, check for 12v to the coil. If you aren't getting 12v to the coil, test backward through the ASD relay.

If you are getting 12v to the coil, then the PCM signal is not getting through or not being sent to collapse the field and fire.