x 340

[gdigger]

I bought it 1 year old had it about 2 years now. It backfires when I cut it off, had it in the dealership twice they replaced several things , but can't find the problem. Now they say it want hurt anything. Any one else had this problem.

 

[CHDinCT]

What engine is in that 340? Fuel injected? Somewhat unusual on newer engines. It's more common on the older ones without a fuel shutoff solenoid. Try idling down for a minute before turning the key off to let any excess fuel. clear the carb. If fuel injected, it shouldn't backfire.

 

[gdigger]

Engine says john deare itorqe, tryed when ideled down still backfires, dealer aculey said to keep throtle up to cut off ,to keep from backfireing.

 

[r8nger]

Sounds to me like I might need a valve adjustment.

 

[gdigger]

What should I do dealer says nothing wrong, that is after they replaced several parts and could not fix it. I know backfireing can't be good.

 

[ctlguy]

This is not complete unusual. Was typically the older units that did this. As mentioned above after cool down of machine increase throttle slightly each time until when you shut it off it does not backfire. Typically this cured the issue. I have a tendency to blame todays gasoline on degradation of internal components quicker than they should be but could be wrong, just my opinion. But increasing the throttle should work for shut down.

 

[gdigger]

Yes keeping the throttle up during shut off keeps it from backfireing. But it definately is not older. I'm going to try high grade gas.

 

[Eric Barney]

The backfire would certainly shorten the muffler life. Possibly even split it open.
Your engine has a carburetor. Fuel injection does not appear on anything (with a gas engine) below an X700. In my opinion, fuel injection should be on all gas engines. It is vastly superior to any carburetor setup. All our tractors could be running better, using less fuel, with much greater reliability.

 

[gdigger]

Thanks for the info, what can I do to solve the problem, should I try a different dealer.

 

[Eric Barney]

I am assuming that your 'backfire' is out the exhaust. During shutdown. That means that: (a) Fuel (Hot fumes) is accumulating in the muffler because there is no ignition spark while the engine is turned off. The engine spins for a few revs and pumps the residual fuel into the muffler. (b) Something in the muffler ignites this residual fuel. (Probably some glowing carbon deposits.) The first solution I might try is: Premium fuel with an additive like Sea Foam. It should clear out the crud in the muffler that could be igniting the fumes.

The primary purpose for fuel cut solenoids on the carburetor, is to prevent 'run-on.' It should not have that much effect on a shutdown backfire. I always prefer to shut off an engine while it is idling. The slower an engine turning, the quicker it will stop when it is shut off.