Hey guys,I've got a 87 six cylinder jeep thats been running rough lately.I have changed the plugs,wires,distributer,fuel filter and the fuel pump.The other day I pulled the air filter out and it was soaked in oil .It's now cutting out and backfiring to the point its not driveable.
I know how much everybody on here loves the g@s burners so thanks for any input.
Steve

 

Check the pcv system thoroughly.

 

could your timing chain have slipped? I drove a car once that was out by one tooth, had no power amd backfired

 

Check the crankcase breather and breather hose for blockage /debris.....also check to see if theres not too much oil in motor.

 

If your breather and pcv system is all replaced and new, the rings might be gone, allowing blow by which is pushing the oil up there. Is there smoke or oil coming out of the dip stick tube?

 

Thanks gentlemen,I checked the hose that runs to the air filter housing and there is a little blow by smoke. I will check the pvc system, and look for smoke out of the dip stick. I will also get the timing checked out. It almost left me stranded last night, it will be running descent and then start lurching and jerking which almost caused me to be run over by a tailgating mini van .
I had a ferd 6.9 that would get oil on the back side of the air filter and it smoked like a train out of the crankcase.

 

If it's running nice until it's been on operating temp for a while it can easily be the PCV thermo controlled vacuum switch. This switch does influence timing too.

Good Luck!

AlpineRAM

 

I was just researching this for my 95 cherokee. evidently there is a factory upgrade for the pvc system, this includes a new line for the pvc and some other parts. On the later units the pvc is part of the valve cover and cannot be replaced seperatly. In reading this one of the problems was a oil soaked air filter due to the small line plugging up and building crank pressure. Ive tried to find the article but cant remember where it was. Call the dealer and ask about this. If i recall the kit was under 30 bucks.
I will keep looking for the part# for the kit.

Good luck.

 

Backfiring could also be caused by a weak spark. Pull a plug wire and hold it about a 1/4" away from the plug or a ground. Start it up or have someone crank it over. If it is a nice fat blue blue spark it is OK. If it is a thin weak blue spark or yellow spark you may have coil or condensor problems. Does that model have points? Now if you get a nice shock while doing the above check, well, guess you can call me a few names. ;D
You could have more than one problem. The oil problem being one problem and you already have some good advice on that one. The backfiring could be a new problem on top of the old one. A timing chain that thas slipped could also cause this problem. Is there any chance that while you were doing work on the engine the distributer was turned a tad?
Keep us posted on the fix.

 

Didn't notice you stated it was backfiring. I had a scout that backfired out the carburator. Took it apart and found a hole burned in the valve. this will probably cause blow by too.

 

Thanks everyone for all the good suggestions. Hopefully I'll get a chance to work on it tomorrow. I will let you know what happens.
Steve

 

1987 ... does it have the stock computer controlled carburetor ? My 85 has it and since the smog system fell off :, it tries to compensate by over-adjusting the air/fuel mixture. End result is it runs a lot like what you are describing. Might be another line of thought in case everything else checks out.

Anyone have a spare motorcraft 2100 carb from a ford p/u or amx ??? This is supposed to be a good upgrade for this problem. (sorry for crowding in on your post).

PISTOL

 

srowen, I had 87 jeep wrangler 258 6 banger and the airhorn on the carb is what went wrong with mine it backfired and farted till I put another carb on it. Cured everything the *********** tried about 6 diff. carbs but they always went bad in about 2 wks. Figured I would do my own wrenching and cured the problem.

 

What engine do you have? 258/ 4.2 or 4.0/??? CUs.
the single throat BBS carbs are none for being problem children on the 258s.

Good luck, keep us posted.

 

Hey Guys, sorry it's taken so long for an update but I haven't had a chance to look at it lately. I think I found the problem with the cutting out and I can't believe I overlooked it. The battery tray bolts had rusted off and was allowing the positive battery cable to arc off a piece of metal . I secured the battery and drove it and haven't had a problem yet.
Hey AlpineRam, that explains the sparks ;D.
Thanks for all the info guys.
Steve