Spit, Cough, Backfire, etc...

Hi all,

I have John Deere LX277 with all wheel steering. It was purchased brand new in year 2000. Other than the occasional carb needing cleaning, it's been operating flawlessly. For the past couple of weeks, if I run for more than an hour, the motor will begin to spit, cough, backfire (at least it sounds like a backfire), will clear up after a few seconds and then do it again but intermittently. Only this time the spitting, etc... will last longer before clearing itself. There is no set pattern to when it acts up. Perhaps some of you fine people on this forum can offer some advice as what and where to look for the problem. Thank you in advance for the help. Roger

high test gas with a quality fuel treatment at all times

Mechanic Mark - Thanks for the suggestion. I appreciate it. What can I do in the short term to rectify this problem? I have begun using non-ethanol fuel. This is the first time since it was purchased that it has run so badly. I should also add that at times it sounds like it's only running on one cylinder. Last fall I put in new spark plugs, air filter, fuel filter, changed the engine oil and new oil filter; all of them are John Deere parts purchased from my local dealer. Roger

Pull the float bowl off & check for water, Drain the tank & refill with good gas.
IF it still plays up get an inline plug tester , fit it and run the engine without the hood ( they are mostly cosmetic ).
Watch the spark tester while mowing to see if the coughing & backfiring coencides with the spark going funny.
This be the case then either the bridge wire between the coil is bad or one of the coils is bad,
Verify by removing the kill wires from the coils .
Problem goes away, wiring problem.
Note you will have to put the wires back on to stop the engine.
This is for testing only, do not run the engine like this for any length of time.