LT180, runs sluggish after about 15 mins

[jb59]

My LT 180 starts running sluggish after about 15 minutes of operation. It makes a sound similar to an auto that has its points missing. I replaced the spark plug and that seemed to be a bandaid for the problem for about a week but it's back to making the same sound. The sound really gets noticeable when the blades are engaged. The tractor starts shaking eventually, so I decided to turn it off and not mess with it again until I can figure this out. Funny thing is, if I don't have the blades engaged, I think it'll run ok.

I'm curious if anyone else has ever had a similar problem. Could it possibly be the carburetor? Just not sure how that could affect the problem which seems to only exist when the blades are running.

Thanks much for any replies

Joe

 

[prosperity]

For a quick test, try running with the gas cap slightly loosened and see if it still does it. If the vent in the gas cap is plugged the gas tank will create a negative pressure after a few minutes of use.

 

[jb59]

For a quick test, try running with the gas cap slightly loosened and see if it still does it. If the vent in the gas cap is plugged the gas tank will create a negative pressure after a few minutes of use.

Thank you for your reply prosperity.

I don't think there's a vent in the gas cap. Am I looking in the wrong area?

That being said....

I tried it (running the engine w/gas cap slightly loose) just a few minutes ago. First I just started the JD and let it run stationary for about 5 minutes, then I took it for a spin around the property for about 20 minutes. It seemed to run better. I then tightened the gas cap and it seemed ok too but that was only about a 5 minute test in itself.

I ran the tractor with the blades engaged and without and everything seemed to be ok. I guess running it for an hour or so would be a better test. I have noticed in my last 2 or 3 times in cutting the grass that its using way more gasoline than normal.

I didn't see too much in the user's manual about tweaking a carb.

Thanks again!

Joe
S.E. Pa

 

[bullbreaker]

Could be different things. For starters I'd run a small amount of Sea Foam through it with premium fresh fuel. As for shaken when blades engauged I would look for bent or extremely worn blades ,bent pulleys or lack of lubrication (grease zerks). Also check for heavy build up of grass/dirt under pulley covers. Just maintenance stuff.

 

[jb59]

Could be different things. For starters I'd run a small amount of Sea Foam through it with premium fresh fuel. As for shaken when blades engauged I would look for bent or extremely worn blades ,bent pulleys or lack of lubrication (grease zerks). Also check for heavy build up of grass/dirt under pulley covers. Just maintenance stuff.

Thanks for the reply bullbreaker. I don't know what sea foam is but i'll get some asap and try it the way you suggest. i did clean beneath the deck, and the blades were sharpened just last week. But I do need to grease it and when I do that, I'll check the pulleys.

 

[bullbreaker]

Seafoam Wallmart or auto parts store about 10 bucks ! Read instructions not much needed to put in. Keep us posted !

 

[prosperity]

Thank you for your reply prosperity.

I don't think there's a vent in the gas cap. Am I looking in the wrong area?

That being said....

I tried it (running the engine w/gas cap slightly loose) just a few minutes ago. First I just started the JD and let it run stationary for about 5 minutes, then I took it for a spin around the property for about 20 minutes. It seemed to run better. I then tightened the gas cap and it seemed ok too but that was only about a 5 minute test in itself.

I ran the tractor with the blades engaged and without and everything seemed to be ok. I guess running it for an hour or so would be a better test. I have noticed in my last 2 or 3 times in cutting the grass that its using way more gasoline than normal.

I didn't see too much in the user's manual about tweaking a carb.

Thanks again!

Joe
S.E. Pa

It may be hard or almost impossible to see on some gas caps. But the tank has to be vented somewhere somehow. If the tank were sealed without any vent, as the engine uses gas out of the tank, air has to come in to replace the area where the gas was. If no air can get in, it will create a vacuum situation in the tank and not be able to feed the carburetor with fuel properly. That is why I went with this solution when you said it runs fine for 15 minutes then starts to falter.

If leaving the gas cap loose continues to work, then try soaking the gas cap in some gas or other solvent for a while.

Edit to add: Here's another way to test my theory which won't cost you anything. Run the tractor as normal with the gas cap tight. When the engine starts to falter/die, shut it off. Then with your ear close to the gas cap, loosen it to see if you hear any air rushing as you open it. If you do, then that is the cause for sure. And also, after you loosen the cap and tighten it again, see if it runs fine for another 15 minutes.

 

[jb59]

You were right....i lowered the deck and cleaned real good. That did the trick. Thanks for your help. Still getting that Seafoam Tuesday.

 

[jb59]

For a quick test, try running with the gas cap slightly loosened and see if it still does it. If the vent in the gas cap is plugged the gas tank will create a negative pressure after a few minutes of use.

Well I found the vent in the gas cap. The cap was plugged up with mud. I don't have to admit that I'm a newbie with these riding lawn mowers. Never had a big enough yard to use one til I moved up here to Pa from Florida a couple years ago.

Any how, thanks for the education!

 

[prosperity]

We're all here to learn from each other. I'm hoping cleaning the gas cap vent solves your problem.