JD LX279 problems

[fowtyfour]

I asked this on another site but got little feedback. Hopefully my luck will change here.

I am new to the forum and like many ended up here looking for help. I have a 2000 LX279 lawn tractor with the Kaw liquid cooled engine. I don't know the maintenance history of the machine as I acquired it last fall with our new home purchase. I do know that it has been used hard.

My problem is that it will run for up to 2 hours and then start running terrible. If I continue to put a load on the engine it will kill. If I allow it to run (no load) sitting there it will eventually smooth out. Sometimes using the choke will help to keep it running. Either way the engine will smooth out after a while if I can keep it running. Usually this starts after about 1.5 hours of mowing. If I put a load on the machine after letting is smooth out it just starts acting up again after a very short period of time. Prior to all this the tractor runs flawlessly. So far I have removed and cleaned the tank, replaced all the gas lines, replaced fuel filter and fuel pump. I also made sure that the fuel tank vent on the gas cap is not plugged. I did a quick cleaning of the carburetor as well but only to the point of removing it, taking the bowl and float apart and spraying it all down with carb cleaner. It did not appear to be dirty at all. As you can probably tell I was convinced that the problem was fuel related but I am second guessing that now.

So now I am wondering if it could be electrical. I picked up a couple new plugs but the old ones looked pretty good. I am really getting tired of this. What could be happening after running for such a long period of time? My plan is to put the new plugs in and see what happens.

Another issue that I don't know if it could be related to this is that the engine will smoke (white smoke) sometimes when I start it. Usually it does this from a cold start but not always. It stops smoking after a minute at the most. I noticed that it was very slowly using coolant. (not good I know) This seems to have stopped since putting in the new fuel pump but I've only run it a couple times since then and it could just be coincidence.

This is getting really frustrating and I feel like I may be throwing good money after bad.

Thanks,

 

[bgi]

From the description, it sounds like it's starved for fuel. I say this because you mention that choking it sometimes helps.

It sounds like you've taken many steps to address fuel problems.

I'll caution you to be careful when this happens because running an engine lean may cause it to overheat or detonate.

There may be some debris getting into the carb jet and blocking fuel flow, or the carb itself may be starved for fuel. Can you check the carb bowl level when it's running poorly? That would confirm that fuel delivery to the carb is good. Maybe shut off the fuel valve and engine immediately, then check to see if the carb bowl has plenty of fuel. Also, I wouldn't know how, but can you confirm that the carb jet isn't getting clogged? Sorry - that seems marginally helpful - I wouldn't know how to do that. If you confirm that the carb is getting reliable fuel delivery, maybe it's time for a new or rebuilt carb?

guessing - hope it helps.

 

[fowtyfour]

I think that is good advice. It has me puzzled because it can run well for so long and then go into this. I plan to soak the carb overnight in seafoam and see what that does.

 

[bgi]

Good luck with this. My 1st Deere machine was a used LX280. it was really nice.

 

[fowtyfour]

I don't know a lot about one lawn tractor vs another but my LX279 sure feels nice when I'm not having these problems. I kind of feel like a liquid cooled engine is overkill in a lawn mower but it does sound nice. Especially compared to what I remember of the old Craftsman I used as a kid. That thing ran forever and I never saw the old man do a thing to it.

I took the carb off and disassembled it. I tried to blow through the port were the fuel line hooks in and there was almost no flow through it. After some carb cleaner and a toothpick, air was flowing freely. It went from popping a blood vessel flow to blowing through and empty straw flow. Anyway, I am hopeful that this will take care of it. I think I'll still give it a good soaking in some cleaner before putting it back together. Probably didn't need that $130 fuel pump.

 

[bgi]

Awesome! that may do the trick.

The water cooled engines will run for many more hours than an air-cooled engine. And they're much quieter.

Men and their machines... er... toys...

 

[fowtyfour]

Well things are looking better. I put the carb back together (after cleaning and a gasket kit) and went out and cut some grass. Went about two hours and it ran perfect. Knock on wood I hope this is the end of my problems.

 

[thebigmo]

Just remember also you need to change the transmission oil to 5W20 full synthetic and also change the bolt that holds the pto to the crankshaft it will break!! Otherwise good dependable tractor liquid cooled.