Kohler 12hp dies under load

danzoJune 8, 2007

Hello, i have a MF1200 with a 12 Kohler it will go until you give it full throttle then dies . the same ,as soon i put the PTO on the same.start and run goes on 1/2 throttle. still stalls no matter when the pto come . cleaned and ajusted carb every where. thanks much Dan

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castoff(Z5 Ontario)

Any engine under load will consume fuel at a higher rate than an engine not under load. IMHO, you either did not clean the carb completely (by soaking it overnight in actual carb cleaner) or you have a fuel delivery problem that is failing to keep the float bowl full at all times.

There are multiple possible causes for that phenomenom. A restricted air vent in the gas cap will cause fuel starvation. An old fuel line can become restricted. Fuel pumps get weak and fail to pump at the same gph as new ones. Substantial wear in the engine can cause pulse type fuel pumps to not work properly. Fuel filters can become clogged.

Plugged air filters can cause an engine to starve for air. Running your engine with no filter for a minute or two under the loading you refer to will tell you all you need to know on that issue.

Electric fuel pumps that put out about 2 to 4 psi can be bought from J.C. Whitney at low cost and can be wired in on the same line that supplies power to the coil of the engine.

    Bookmark   June 8, 2007 at 9:21AM
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I agree, sounds like fuel starvation.

I would go ahead and replace the air and fuel filters first (good PM in any case).

    Bookmark   June 8, 2007 at 9:28AM
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it does the same with or without air cleaner ive put a tank set up for gravity flow still does it I'll pull thr carb and clean 3rd time thanks Dan

    Bookmark   June 8, 2007 at 12:01PM
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I'd look for vacuum leaks between the carb-intake-block.
IF this is an old engine, look for excessive slop in the throttle shaft.

    Bookmark   June 8, 2007 at 1:44PM
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Be sure to set the float per manufacturers spec when you take the carb apart again. Also shake the float to make sure it isn't leaking.

How's the gasket to the engine? If that is chewed up replace it (e.g. vacuum leak as Bill Suggests)

Does this have a manual choke? If so, does turning it on slightly help?

    Bookmark   June 8, 2007 at 3:44PM
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How about new plugs?

    Bookmark   June 8, 2007 at 6:10PM
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This was burnt valves once upon a time for me and my old 12 HP Kohler. Still, I'd eliminate the cheap stuff first as suggested above.

    Bookmark   June 8, 2007 at 6:56PM
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If it is an old k series engine, adjust your valves and
clean and adjust the points. Post the engine model numbers
for more specific help. A spec number would be helpful too


    Bookmark   June 9, 2007 at 6:22AM
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the engine # k301aqs 4758D thanks

    Bookmark   June 9, 2007 at 7:48AM
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butchs_hobby(s texas)

My 1450MF with the K series Kohlor sure runs better and smoother since I adjusted the valves. I'm going to do the same on my 1650MF this weekend. Check the easy stuff first, look at the points--clean, replace,and/or adjust as needed, try a new plug making sure it's the right one for your motor. Take the fuel line off at the carb, stick it in an old water bottle ands start the motor, that'll let you know about fuel delivery. Is the battery good? The old Kohler K is a point and coil set up so battery voltage does matter. If you had a burnt valve it won't run good at low speeds, wouldn't have much power if it does run. Those old Kohler K's where solid motors, both of mine are 1972 models, never overhauled but I did have to replace the carb on the 14hp(throttle shaft worn out), otherwise no problems with them.

    Bookmark   June 9, 2007 at 10:27AM
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thanks all, did the valves replaced intake gasket had small leak,the valves were the problem thanks Dan

    Bookmark   June 10, 2007 at 10:54AM
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