TIMING

[jeephack]

What would be the most common cause for a 4.0 engine to jump timing. I drove my Comanche

to the woods this morning to go hunting. Everything ran fine. When I got ready to leave,

The engine would turn over, but it would not fire. After some tinkering, I finally got it to

start, but it won't idle, and it runs extremely rough. Not to mention, it smokes like the woods

is on fire. I know that the timing has somehow gotten waaay off.

[Geonovast]

Really the only way it could have happened is if the chain got loose from stretching, and jumped a tooth.

[mvusse]

Or gears on one of the sprockets have worn away.

[jpnjim]

Did you do any water crossings?

One of my MJ's would get water in the distributor cap if I even went close to water,

magically water would collect on the underside of the hood directly over the distributor, and drip-drip-drip,

followed by rough running & stalling.

 

I had to squirt WD40 into the cap after every water crossing,

till I got one of those Ford 5.0L rubber distributor wrap around covers.

 

Other's have successfully sealed the cap, and extended the breather for the same result, but I like the 5.0L style cover.

[jeephack]

Now it has me really confused. After I came home and gathered up some tools and

parts, and went back to start working on it, It starts right up and runs smoothly.

Seems I have an intermittent problem. Well, the search begins! Will share when the

problem is located.

[Automan2164]

Did you do any water crossings?

One of my MJ's would get water in the distributor cap if I even went close to water,

magically water would collect on the underside of the hood directly over the distributor, and drip-drip-drip,

followed by rough running & stalling.

 

I had to squirt WD40 into the cap after every water crossing,

till I got one of those Ford 5.0L rubber distributor wrap around covers.

 

Other's have successfully sealed the cap, and extended the breather for the same result, but I like the 5.0L style cover.

 

:agree:

 

Rob L.

[jpnjim]

 

:agree:

 

Rob L.

 

double :agree: :agree: now that the problem mysteriously vanished. :yes:

 

 

It's weird tho, that I had 4 different XJ/MJ's that saw regular trail use, and only one had an issue with the cap regularly taking in water, and running rough/stalling.

 

 

Crappy old, dried out plug wires can also cause problems when they get wet, so even if the cap is dry,

it's still probably water + ignition related.

[mvusse]

Hate to sound repetitive, but I agree with the above posters. Obviously not a timing problem, but a misfire problem instead. I'd start by replacing the distributor cap (and what goes with it: rotor button, plugs and wires). It should be done as regular maintenance, but when was the last time it was done?

[jeephack]

Hate to sound repetitive, but I agree with the above posters. Obviously not a timing problem, but a misfire problem instead. I'd start by replacing the distributor cap (and what goes with it: rotor button, plugs and wires). It should be done as regular maintenance, but when was the last time it was done?

This was done back when I first bought it in 2007. I've only put around 3000 miles on it since. This is not a daily driver.

It's my toy/hobby/project/mental exercise. I had another distributor with me when I went back to retrieve it from the

woods. Didn't put it in though, because it started and ran O.K. What really had me appalled and taken aback was the

amount of smoke it was putting out while it was misfiring. Looked like Seafoam x 2.

[jeephack]

After some consideration, I decided to replace the fuel filter. The truck ran much better.

Thought I may have found the problem. After a short hunting trip last Saturday, after I

returned home and cut the truck off, it wouldn't start. I tried to start it every evening

after work to no no avail. This afternoon, having a little more time to tinker on it, I found

that it was not firing. On a whim, I unplugged and cleaned the cps connector. Truck

started and ran fine. Might be on to something here.