Wingin1t

Ok so I was mudding 2 days ago and near the end I went through a pit full of water, water was about 4 inches from rockers. As soon as I hit the middle of the pit the jeep just cut out. I tried turning it over a few times and nothing. My buddy pulled me out and we started trouble shooting.

We found after a while that there was no spark from the coil but the was power going to the coils plug. So yesterday I bought a new coil and put it in and it still would just turn over and not start. After checking the cap and plug wires and coil harness plug we tested for spark again, this time there was spark. We connected to coil plug to the distributor cap and started the jeep, it ran for about 2 seconds then cut out. After an hour or so of trying to start it and wiggling connections we still get same result: runs for a few seconds or sounds like it wants to start and keeps turnin over. The rotor is fairly new and the distributor is fairly new along with the coil. No water got into the air filter from what we could tell, the intake tubing was dry and so was the filter. We get power to the green/orange wire coming off the coil harness and we assumed the black wire on the harness was a ground but has no continuity with a ground, instead we were seeing power as well in the black wire. We trace the wire to the ecu and it get continuity from the coil harness to the ecu connector on the ecu. We are getting fuel to the fuel rail still and are stumped, any ideas? Anyone had this issue before?

tjwalker

Crankshaft position sensor is a suspect. Without that input signal going to the computer, you won't have spark and you won't have fuel going TO the injectors, even though you may have good fuel pressure at the fuel rail.

JamDeeper

Water in the gas?

Cherockee

I too would suspect a sensor. I believe that the computer puts power to the coil and fuel injectors for 3 seconds each time the key is cycled to the start position. If the computer doesn't see both a crank sensor and/or cam sensor it will cut power to both fuel and spark- which sounds like what you're experiencing.

Even a bad connection due to water or corrosion on either connector will cause you some problems

Wingin1t

Ok thanks

stev-o

Cps for sure sounda exactly like a cps issue

stev-o

The cps runns right by your exhaust so it could have gotten a little bit hot and cut out on u

DFlintstone

On my (90 Renix Jeep), the second wire from the front, a black one, is grounded.

stev-o

A new cps is $31.80 I just traded mine in for the lifetime warranty and they replaced it with no questions asked at autozone

Wingin1t

On the ecu connection?

Wingin1t

I'll look into the cps. I know mine is kinda flimsy at the cps side in the rubber boot. Just never had an issue like this before the pit of water.

DFlintstone

On my plug on the ign mod. the second one back is black, and grounded.

Wingin1t

well i replaced the CPS yesterday and it still has no spark... My buddy and I are really stumped on this one guys... any other ideas?

Cherockee

Things to look for:
Dark Green/Orange wire going to the coil has 12V when the ignition key is turned on.

Orange wire going to both the crank and cam sensors have 5V for the first few second when the key is turned to start/crank

Continuity between ground and the Brown/Yellow wires for each sensor

The sensor output wires (tan/yellow for cam and grey/black for crank) will show pulses on them when the engine turns over. Probably hard to see this with a digital meter, analog works best for this. Power for the coil comes from fues 20 in the PDC and power for the sensor comes from connector 1 of the PCM, pin #17.

I copied this from a reply I made to someone else having simular symptoms. If you can't find your answer here you may want to replace your PCM/ECM

Wingin1t

ok thanks ill give it a shot tonight and let you all know the outcome.