Jeep Cranks, Won't Really Start

757 Views 10 Replies 5 Participants Last post by CP30, Aug 26, 2017

Jeeper736

Discussion Starter · Aug 22, 2017

To start this off I was going on a trip and leaving the jeep behind, I was looking under the hood for some reason and left it open. It rained that night and it was shut the next day.

Apparently the light bar was on for quite awhile, I traced it to the relay getting waterlogged and shorting out, this fried the relay but the rest is good, the light bar is connected to the battery terminals, just including this in case it could've messed something up.

So! After I got back a few days later it started up fine, on the way to a friends house it stalled out, I stopped and it started right back up. Since it started back up I figured it was water in a connection and would evaporate out. Stupid I know. On the way back it got worse, the jeep kept stalling sometimes right after start, but mostly at idle speed or when I gave it more gas. It stayed running fine when I just kept it at a consistent speed. After one of the shut down start up cycles it threw a code for the camshaft position sensor being disconnected, but it went away on the next shut down start up.

The next day I tried starting it again, but it wouldn't turn over, it cranks fine though. I cleaned up the battery connections as well as blasted the fuse box, the camshaft position sensor connection, the oil pressure sensor connection, the three harness connections on the passenger firewall next to the engine, the three connections that plug into what I think is the PCM (the box on the driver side fender), and the coil rail connection.

I also tried replacing the camshaft position sensor, that didn't help. I believe I checked the crankshaft position sensor, but it's connection seems to be in a different place than I keep finding online. The sensor is at the 1 o'clock position looking from the front and the connection is at around 3 and behind it attached to a bracket on the transmission. I tested pins B and C on that connection and got a reading of around 60 M ohms, which I believe is higher than the proper testing range.

One more weird happening is after cranking it some times the oil pressure gauge jumps to above 80, but goes back to just above 0 after I turn the jeep off then on again.

Any help is appreciated and I can upload some photos if need be.

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CJ7-Tim

· #7 · Aug 24, 2017

I would not pour any gas into the intake.

If necessary, a 1/2 second burst of starting fluid will tell you if the engine will run. Checking/testing fuses and relays is basic troubleshooting and where you should begin problem solving.

Letting the battery run down will delete the idle settings from the PCM, and there will be difficulty starting. You need to depress the gas pedal about halfway while cranking and them keep you foot on it until the idle steadies. If nursing the gas pedal does not help it start, you will need to follow up on the Cam Sensor code, and properly test the Crank Sensor.

1997-2001 have an in tank fuel filter that is not changed unless fully clogged and there is low fuel pressure.

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CJ7-Tim

· #10 · Aug 26, 2017

Be safe, smart Cherokee owners DO NOT pour gasoline into the fuel injection intake. If there is a backfire, flaming gasoline could fly out of the intake and set the engine bay on fire. One shot of starter fluid, 1/2 second in duration, is all that would be necessary to confirm ignition and running, and any starter fluid backfires would not set flame to the Cherokee.

If a simple to perfrom fuel pressure test shows 49 psi +/- 5 psi of fuel pressure when the engine is running, the in-tank fuel filter does not need changing for any reason.

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