Crank Position Sensor

[JeepMonkey]

A friend of mine has a '99 TJ, 4.0 that won't start. It's turning over, but won't fire. He pulled an injector and verified there is fuel. He said that he's going to replace cap and rotor if there is no spark. I told hime that it may be the CPS. Anyone have any experience with this?

	Crank position sensor A crank sensor is a component used in an internal combustion engine to monitor the position or rotational speed of the crankshaft. This information is used by engine management systems to control ignition system timing and other engine parameters. Before electronic crank sensors were available, the distributor would have to be manually adjusted to a timing mark on the engine.

[currupt4130]

Yea, it's a possibility. Bad cap and rotor wouldn't cause it to not run. You'd at least hear it popping and trying to go unless the cap was shattered or something silly.

[yjdave]

It's the cps. That is the only thing that controls spark to the coil. You checked the coil ooutput right????????

	Crank position sensor A crank sensor is a component used in an internal combustion engine to monitor the position or rotational speed of the crankshaft. This information is used by engine management systems to control ignition system timing and other engine parameters. Before electronic crank sensors were available, the distributor would have to be manually adjusted to a timing mark on the engine.

[Bounty__Hunter]

Could also be the ASD relay.

[JeepMonkey]

They were supposed to work on it yesterday afternoon. I was unavailable, but I'm going to find out asap what they discovered.

What is the ASD relay?

[Bounty__Hunter]

auto shutdown relay in the pdc.

[luckyned]

Just lost my 95' while attempting to drive it back home from camp. Just quit running. Never a lick of trouble from it before. Cranks but no start. Would restart on my arrivals but only run for 3 min..then quit and no-restarts. Fuel-pump in tank (can't or won't attempt with my lack of knowledge) so I pulled filter to test for constant fuel-yes fuel. Spark? Well, it apparently does at times. Pulled a sparky to watch and decided it works. Checked auto-shutdown..ok. Changed crank-position sensor..Zoom! Thank God, cause my tools and skills are lacking. I love the internet. Maybe this helps someone else.

[currupt4130]

Also had a similar experience, but the magnetic pickup on my distributor had gotten dirty and would inadvertently cause the engine to shut off and not start for a day or two.