Cub LTX 1045 backfires when idling

[betterdays]

I have an LTX 1045 Cub. When the engines cold everything is fine, but after mowing a few minutes and stop and let it idle it begines to backfire out the exhaust. I am wondering about a timing issue, but runs fine at full throttle mowing. Anyone with a solution?

 

[Carl_NH]

Could be a valve adjustment or a carb adjustment. Usually they suggest turning these off at mid throttle to prevent/elminate the backfiring.

This is due to (I think) the unburned fuel that is resident in the intake after full thottle operation causes the backfire.

If it runs and starts easy, and doesnt backfire at mid throttle I would leave well enough alone..

 

[betterdays]

Thanks for the reply. Old school ideas always had me throttle back before shutting off. Guess thats gone out the window these days. Your probably right. If it ain't broke, don't fix it.

 

[Carl_NH]

Yes - my 1811 (18HP Kohler Magnum) will backfire if I shut it down or throttle it down quickly when its hot.

 

[betterdays]

After studying this issue a few mowing times I decided to remove and inspect the carburetor. Turns our the fuel solenoid mounted under the bowl of the carburetor was seized and not functioning. I replaced the solenoid ($70.00 and the parts man didn't even feel bad about the price). But now this tractor runs smooth at idle and full throttle. No backfire, popping or otherwise. Hope this helps the next guy with a similar issue. Hint, if you find any of these solenoids used or a going out of buisness Cub dealer I suggest you grab them.

 

[rcbe]

?? a bit hard to understand. That solenoid is an afterfire solenoid - which when energized, retracts and opens fuel flow to the high speed (load) circuit and closes off same when de-energized. The idle circuit is left undisturbed. it's purpose is to limit raw fuel fumes from entering the exhaust/mufller passages during shutdown and making the big "bang".
In the proess of changeout, you may have dislodged a small piece of trash from one of the carb passageways, clearing up the performance problem...?