i was towing a jet ski today after about a half hourwe were smelling something burning it wasnt strong but u could smell something burning couldnt track the smell went away qiuckly after i shut the truck off drove the truck home(bout 25 miles) without out the jet ski and no smell should i be concerned bout what ever this was

 

when the last time you greased the wheel bearings on the jet ski trailer ? think you could of accidently drove around with the E brake on ?

 

if your jeep is a 5spd the clutch plate could've produced the smell b/c of slippage

 

Could have been an ambient smell considering that it came and went quickly and has not returned.I get the same way sometimes while driving.

 

Trans/Rear end/Brakes Overheat ... Take your pick.

 

We've got crazy birds in Texas, and I had a similar smell with my XJ. Turned out to be a nest on my intake manifold. It seems obvious, but look over the engine compartment really well.

 

If its a complete stock xj and your towing "at capacity" you could just be heating up your trans.
and then you drove home without towing it stayed plenty cool.
could try changing out your fluids or adding a trans cooler (helps with towing)

I notice when i drive in 4wd i have a smell as well, but as it turns out its my front axel fluid heating up. (i do need to get on that) could be the same...

 

Check trans fluid level.

 

happened to me in a similar manner, although my smeller doesn't work like it should. I did however notice in my rear view mirror that my XJ was doing its best to mimic a 007 fogger. I just had a small trailer with an ATV on it, but I had forgotten to take it out of Overdrive. Pushed ATF out the filler tube and got all over the exhaust. Probably won't rust now, but could have done without it. My suggestion would be to change oil and filter, dump in some Lucas tranny fix, along with the required amount of Dexron III, and take it out of overdrive when towing. Like one other post mentioned, a cooler would more than likely help also. Bigger is definitely better when it comes to this. Hope some of this helps. Good Luck

 

I used to get the fluid out of the dipstick tube on my patrol Cherokee when I was running it really hard up a mountain pass. Freaked me out the first time it happened. I'll bet it was quite a sight, fully marked State Patrol Cherokee with smoke pouring out the back going up a pass.