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We have a 2010 John Deere X300 with a Kawasaki engine Model FH491V-DS04-R. It has 279.4 hours on it. It starts and runs fine when you first start mowing, then when it heats up it starts to run very sluggish. If you let it sit and cool down it will run fine again.it's almost like when you go through tall grass and it bogs down, but it is not in tall grass. I have cleaned out the mower deck, checked the belt and belt tension, replaced the fuel filter, checked the air filter (good), cleaned out the carburetor, and replaced the spark plugs at the beginning of the season, also checked the coils by removing one spark plug wire at a time. One weird thing when I rechecked them is that the spark plugs all around the outside of them where you screw them in, the metal is all white, like they are heating up. The engine area is clean and nothing looks clogged so we are at a loss and looking for suggestions. Thank you!

~F

Schillfam,

Remove the tins around the cylinder, check for grass blocking the cooling fins. Also, make sure the gas cap vent isn't plugged (stopped) up. There may be other things to consider. However, I'd start there.

Max

Are you sure the carburetor isn't getting bogged down by anything? How dirty was it when you first cleaned it?

greenmowers.org said:

Are you sure the carburetor isn't getting bogged down by anything? How dirty was it when you first cleaned it?

Click to expand...

Surprisingly It was not dirty at all.

shillfam,

It is running extremely lean as mentioned above, the carb isn't delivering enough fuel to cool the cylinder atmosphere. Clean the carb extremely well. Make sure all circuits are open.

Max

Check for blocked fuel lines had one ran good for a little while then start going down bad filter and bad line was the cause. But also can't rule out the coil.

Coils don't go bad that often. Take the gasoline line, an enclosed fuel cell of some sort foreign to the machine and run a line from the remote fuel cell directly to the carb. Run the mower WOT for the amount of time the original fuel cell begins to make it run lean.

Then you'll know if your fuel system in total is your problem and the coils are ruled out as well.

Make sure you mount the remote fuel system securely so you don't set yourself and the property on fire by trying to carry a remote tank in your hand while operating the machine.

Have the coils to go bad a lot here as they get weak and won't fire properly also fail to fire under compression quite often.

That test will give you an idea then whether it is fuel or your coil.

Yes I agree to rule out the fuel by using another tank will rule that out as being fuel delivery issue. Some unless the pump fails or the anti-after fire solenoid is failing. Then then problem will still be there. Needs to get 2 inline spark testers and run them while the test is done to rule the coils right out. :thumbsup:

Always good to test for fire at the plug. Rule out the fuel pump all the way to the anti-backfire solenoid with the remote tank above the carb using gravity feed.

Good luck in all the above tests.