vadergator

i've been through hell with my 97 GC Laredo 4.0L 2WD for months now. no matter what parts i throw at it, the problem persists. i call it the " 1 hour mystery syndrome ". jeep runs & functions PERFECTLY in every way. idle, fuel delivery, spark, acceleration, fuel consumption, handling, you get the picture. no matter how long this ***** from hell is driven, if i try to start the jeep after it's sat for an hour, it ain't going nowhere. crank her up in 45 minutes or less, she runs PERFECT in every way. obviously in life, you can not accomplish every thing in 45 minutes or less. i've done a lot of walking home the past 6 months. 3 shops & 15 " certified " mechanics later, i'm no closer to having this problem fixed. amazingly, the jeep " self - repairs " itself over night without fail. it is more dependable than playing the lottery. i ran into an old feller today, i thought he might be crazy. that's why i have a question for the old seasoned mechanics on here. he said that he had the same type of jeep with the same problem ( except for the length of time issue ). said he threw every part known to man at it. problem still there. sounds familiar. he did a lot of walking home too. anyways, just by pure chance one day, a guy told him to change his oil pressure sending unit. he did. WALLAH!!! problem solved. he had his old jeep back. here's my question. can a bad / going bad oil pressure sending unit cause a " mystery electrical short " that would cause a jeep to go into shutdown mode that results in no spark, until the next day? can the PCM detect something's not right (oil pressure related), and perceive it as a threat to the engine's integrity, without throwing any warning light or trouble code that would cause a no spark issue til the next day? appreciate any & all input.::fur ious::na ughty:

Bustedback

Have you replaced the cam sensor/pickup coil in the distributor?

vadergator

yes. i changed it out and even did a quick swap ( just in case one's defective attempt as well ). still same problem. i have noticed that my oil pressure gauge does fluctuate some. while idling ( @ warm-up and stopped at lights ) it reads about 38 - 40 on the gauge ( just shy of dead center ). but, while accelerating on the highway at various speeds, i've seen the gauge rise to about 50 ( i'm guessing here cuz there's obviously not a line at this point of the gauge) and drop back to about maybe 32, before returning back to about 40 again. i found some oil on bottom of oil filter and thought it was due to valve cover gasket leak ( just changed it out 2 weeks ago ). not losing oil according to my oil dipstick. do you think the oil sending unit can cause a no spark shutdown? i didn't know if the guy was crazy or not. i was hoping that he wasn't.

Bustedback

The oil sender should not cause a no spark condition.