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Curtis B.
Curtis B., Technician
Category: Small Engine
Satisfied Customers: 28657
Experience:  have worked on and around most engine models for 35 yrs./Polaris ATV expert
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I have a 26 HP Kohler PRO Courage Twin Cylinder engine & 54"

Customer Question

Hello, I have a 26 HP Kohler PRO Courage Twin Cylinder engine & 54" mower Deck and having issues with lost of power under load, normal grass or going up slight incline to the point of almost stalling. I've changed the plugs, removed the air filter, changed the fuel filter with no change. you can hear the engine bogging down.
Mower always had power lost when cutting to much grass but never had any issues with normal cutting and inclines.
I purchased in 2006 and have 400 Hrs.
Submitted: 1 year ago.
Category: Small Engine
Expert:  Curtis B. replied 1 year ago.

Good morning. Have you ran a cylinder balance test? Loosen the spark plug wires, and with the engine idling, remove one wire at a time. The engine should continue to run. If engine dies when one wire is removed, the opposite cylinder is not firing. Check it for spark. With the Kohler twin, it can have a bad coil, letting engine only run on one cylinder. Causing the low power. If you have a bad coil, Kohler recommends replacing both coils to the newer style coils.

Customer: replied 1 year ago.
Expert:  Curtis B. replied 1 year ago.

Can you run the test when the engine is hot and acting up? It may only do it when engine is hot.

Customer: replied 1 year ago.
Expert:  Curtis B. replied 1 year ago.

Let's try that, thanks.

Customer: replied 1 year ago.
Curtis, ran mower in meadows for 15 min. when I turn blades on, cutting short grass engine spudders and slows down, turn blades off and engine ramps back. pulled one spark wire than the next again engine slowed no spuddering, ran steady.
Customer: replied 1 year ago.
ran another 15 min. up and down 15 deg. incline without blades on and engine ran fine. soon as I engage blades engine spudders and losses power. pulled plug wires again, idel slowed but no stall.
Expert:  Curtis B. replied 1 year ago.

So it does not seem to be the coils failing. So may be a fuel problem? Gets better if you stop the blades? Does working the choke help or hurt? I wonder if the supply if fuel from the tank is adequate? Can yu make a test line and attach it to the fuel pump inlet port, nd drop it back into the fule tank filler opening for test, bypassing the tank and the outlet hose?

Customer: replied 1 year ago.
I'll try the choke while cutting and if I can find a hose i'll connect to the fuel pump inlet and dip into the gas tank, thanks
Expert:  Curtis B. replied 1 year ago.

If that makes no difference, tat leaves the electric solenoid in the base of the carburetor, Best test for it, is to remove it and disable it by removing the inner parts.

Customer: replied 1 year ago.
Curtis, I ran the blades and throtteled the choke, it wanted to stall. although I ran the tractor up and down the meadows with the blades running and it seems to have gotten better. I don't have a fuel line long enough to do the other check but thinking I'll change the lines on Tuesday inculding the vacuum line to the pump. did notice that fuel filter isn't 100% full. after replacing the line I'll bleed to completely full. thanks for your help. have a great holiday.
Expert:  Curtis B. replied 1 year ago.

Fuel filter will never show to be completely full, so don't let that be something that worrys you.

Customer: replied 1 year ago.
what does the solenoid do?
Expert:  Curtis B. replied 1 year ago.

The fuel solenoid is anti-backfire solenoid, that closes the main jet in the carburetor when it closes. Used to keep engine from backfiring when key is turned off hot.

Customer: replied 1 year ago.
Good morning and happy holiday,
I haven't looked at the fuel selenoid yet but know that the engine does backfires when I shut it off. I'll work on it later this morning, thanks.
Expert:  Curtis B. replied 1 year ago.