I have unusual problem with my Jeep and has gone on for some time and basically driving me crazy trying to figure it out. It runs sweet on the highway but as soon as I take it off road it starts to run very rough. Stalling out, backfiring etc. I'm not sure if it is from something getting wet or not. I'm assuming it is and looking for help/suggestions what to start looking for or at. It's been doing this for a while now and I've replaced rotor, cap wires plugs and ignition module. Any help appreciated before I lose my mind...It's a 78 CJ5 with 360 V8, T150

What carb you running?

Sounds like an advance, or carb issue to me. But what do I know.

OFFROAD= dirt roads? bumpy dirt roads? offcamber? up hill? down hill? Or just as soon as it leaves pavement?

MJ

Tricky one...sounds like terrafirmaphobia to me!

It's the Motorcraft 2100 2 barrel I think. Why would it only act up off road?

weak float springs maybe?

Originally posted by JeepManInNJ
It's the Motorcraft 2100 2 barrel I think. Why would it only act up off road?

Float level too high.

If the float level is too high, is the bouncing around off road causing it to have these problems? I can lower the float level and see what happens, but don't understand why this would make a difference?

I'm not sure I understand why it has no problems on the street but does on the dirt?? It runs great till I go off road. I know it sounds nuts but this is what is going on...grimlins???

could be loose wiring ............

I've checked wiring to the coil and it is ok. What other wiring should I look at?

what exactly are you doing when it gets stupid?

are you just bouncing, or did you just go through a big puddle or what?

-web

check vacuum before you spend any cash. I know you said it only acts up off road but think about it, you are going way slower off road and with less rpm then you ever do on highway

It seems to happen more often after going through water. It has happened just driving down flat trail wit hsome whoops. It's got me totally at a loss to figure out. Thought someone on here may have had a similar problem. If it does it more after going through water, what should I be checking? How can I rule out Carb short of changing it? I would think that a card problem would happen all the time?

I have been through a lot of the same troubles with mine...First thing I'd check, is the carb. Pull it off the intake take it apart and clean the mess out of it. More than likely there is a ton of crap in it. Buy a new fuel filter as well. Chances are when you are bouncing around you are moving the dirt around in the carb. Even if you have never done anything like taking a carb apart, they are relatively easy so don't shy away...Good Luck. (You might also feel as though you have gained about 20 hp too.

Originally posted by JeepManInNJ
It seems to happen more often after going through water. It has happened just driving down flat trail wit hsome whoops. It's got me totally at a loss to figure out. Thought someone on here may have had a similar problem. If it does it more after going through water, what should I be checking? How can I rule out Carb short of changing it? I would think that a card problem would happen all the time?

Runs bad after being in the water = Probably a wet distributor/wires/ignition module. Dry it out and seal off the problem area (dielectric grease on both ends of the plug wires helps, so does spraying them with a little WaterDisplacement 40.) If it's the ignition module, get a new one.

Runs bad after bumps = floats too high or possibly one is stuck. Adjust/rebuild the carb as necessary. A little foam in the bowls (below the floats) helps to prevent splashing.

HTH,
Jake

I've replaced the ignition module already and same problem exists. Going to take carb off tonight and clean out real good and check floats. If that doesn't solve problem I'm looking to replace carb and go from there. I'll try the water proofing advise too. Short of these I don't know what else to do or try...

I'd dry out/seal up the distributor first. 9 times outta 10 that's the culprit in a runs-shitty-after-getting-wet type of situation.

If you have a vacuum advance arm that you need to seal around, a dollop of dielectric grease can help there too. It seals out the water, but still allows the arm to move in and out of the distributor. I had this problem on my old 258 until I sealed it up.

HTH,
Jake