91armygreenXJ

i have a 1993 jeep grand cherokee, the jeep will start after sitting overnight but after i take it to the store and go to fire it up to go home itll start for a second and shut off and wont fire up again. now i know i have a bad O2 senosr, i have the new one and im putting it in this thursday, my question is if youve had a bad O2 sensor for so long, wouldnt it cause the jeep to load up with fuel and flood it and it wouldnt let me start it warm or cold for an extended amount of time right? the grand is my only mode of transportation and i just would like to know if it should be okay after the O2 sensor is replaced or if i need to get something else too possibly. thanks for your guy's time and help.

xjcrazy

If it has a crankshaft position sensor it could be working intermittently. My cps drove me crazy cause it was bi polar, so one day i pulled it and the wire were showing and shorting out when they touched.

Firestorm500

Fuel filter clogged? Weak fuel pump?

DFlintstone

My 90 started all sorts of ruckus. The whole works. It would hesitate, miss, pop back out the intake. (the confetti blowing out the grille is how I found the mouse nest in the air cleaner). No start a few times. Run like a (frightened) ape if you floored it, but stumble on even throttle. Or run fine for days. Found that most of the usual suspects all seemed to be about $50 each, and some are a ***** to change. I didn’t want to just throw money I didn’t have at it, so I just did normal tune up stuff. Odd symptom (you may or may not have). Could start and run all day , no problem. Turn it off for 2 minutes then “the tantrums”. The sitting business really had me. Oil dripping around the CPS sensor, engine heat migrating to the coil or TPS or something? Something involving the manifolds and a vacuum leak? Catalytic converter. Had to be heat migrating while it was off. It took over a year to figure out that the heat shield over the manifolds was expanding into the injector wires at the front.

CattyXJ

I would grab a multimeter and start checking all the sensors, starting with the CPS. There's write ups on here about how to do it, and it takes the guess work, and throwing money at it out of the equation. If you get a Haynes manual it also will outline testing procedures for you. I tried the shotgun method for a long time until I took someones advice and got the testing tools!

Slick761

Holy crap! Not something that normally comes up! For the op 4.0 cps is notorious. Sometimes it only does it hot because of heatsoak as stated above pull and check the wires for damage. Beyond that an easy way to.narrow it down is to gt it hot and turn it off. When it won't start pour a little gas in through the intake to prime. If it starts its fuel related. I'm really thinking crank position sensor though due to the fact it won't even POP? If it won't start and you put fuel in and it still won't start I would put all my money on that horse. Check rockauto.come for amazing prices and prompt service.

DFlintstone

NO! Guess I didn't make myself clear. I FOUND that the heat shield was expanding as it absorbed heat while parked! Then I would come out of the store, start it then have the problems. It was pushing, ever so slightly into the bottom of the gang of injector wires coming over the front. Took forever to find, 30 seconds to fix! (starting, running, normally it would not get as hot with the air-flow)

Slick761

I got that. That's a strange problem I haven't seen!! One to store in my archives lol. Unfortunately I don't think the 93 grand has that nifty little heat shield..... were lucky to have it though as it combats heat soak to the injectors. Sorry kinda bad segue from your problem to my opinion on the op. And the mouse nest!!! Little critters were having a fume party

DFlintstone

I do confess to being puzzled bu the white stuff blasting out of the front!
The CPS was years ago, so you sort of hit it.

OK army green, I said my bit, I'll "but out" of your thread