LA Fouled Plugs.

[TSX]

My John Deere LA starts easily and runs fine for about 30-45 minutes and then quits. The spark plugs are carboned up but the electrodes are not bridged over with carbon and I have a very weak or no spark. Let it set a while and put in new spark plugs and it runs fine for another 30- 45 minutes and quits again. The magneto has about 20 hours run time on it since being profesionally rebuilt. What do I need to do to fix this situation?

 

[Husker44A]

I would check compression. IF you have 100 lbs or better it should run ok. Make sure that your mag points are not burnt, may even emery cloth your points. Also, check the valves make sure they are up to snuff and not leaking. Have Number 1 piston up on TDC. With air blow-gun with a rubber end put air into the cylinder and listen for leakage. Should hold 100-50 lbs depending on what the engine is like for wear and air pressure. Also could be a fuel problem. Make sure you have a good stream of fuel from tank to carb. Make sure that your float is NOT sticking. Thats what it sounds like to me is fuel but just my guess. Good Luck..

 

[Hotflashjr]

Have you timed the mag right? I agree it sounds more like a fuel problem, but double check your mag timing. The owners manual tells you how time the mag both off and then on the tractor. Even though it was professionally rebuilt, may be worth looking at this as it was the last variable it sounds like changed.

 

[Mike M]

Sometimes you do get bad parts,even if they were changed when the mag was rebuilt they could still cause weak spark.

The carb. may have the wrong jet in it.

 

[Hotflashjr]

You got it! Especially if they didn't bench test the mag or test it on another tractor before they sent it out!

 

[Hotflashjr]

You got it! Especially if they didn't bench test the mag or test it on another tractor before they sent it out!

 

[36 Coupe]

10% gas needs hotter spark plugs.Prolong idling can gas foul plugs.