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Curtis B.
Curtis B., Technician
Category: Small Engine
Satisfied Customers: 12592
Experience:  have worked on and around most engine models for 35 yrs./Polaris ATV expert
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Kohler ch25s wont run at full throttle

Customer Question

kohler ch25s wont run at full throttle
Submitted: 8 months ago.
Category: Small Engine
Expert:  Curtis B. replied 8 months ago.

Is rpm down or it has no power?

Expert:  Curtis B. replied 8 months ago.

Page 26 in the manual link shows the rpm adjustment. And page 28 shows the governor.

Expert:  Curtis B. replied 8 months ago.

If engine is not developing the horse power, then check each cylinder for firing, by removing ne spark plug wire at time while engine is idling. If engine dies when wire is removed, the opposite cylinder is dead. Check for spark and compression.

Customer: replied 8 months ago.
tested spark by grounding each cylinder plug. Looked a bit weak, cleaned plugs, and it ran at full throttle for about 3 minutes, then back to the same symptoms; can get it started, but it will not let me advance the throttle.
Customer: replied 8 months ago.
At first, it would not run without the choke on, and wouldn't let me throttle up. Tried to adjust the carb, but there is nothing but idle screw, nothing for fuel mixture...?
Customer: replied 8 months ago.
New fuel filter, new plugs
Expert:  Curtis B. replied 8 months ago.

Does the carburetor still have the electric fule shutoff solenoid? Is it fully opening? It plugs the main jet and can restrict the fule. Is there a full flow of fuel to the carburetor from the fuel pump?

Customer: replied 8 months ago.
Well,..It "acts like low fuel, but it spits out fuel when it stalls. But maybe thats normal when it stalls out.
Expert:  Curtis B. replied 8 months ago.

One thing to consider, could the exhaust be restricted? It starts out good, bit gets worse as it runs, that is typical of a plugged exhaust system.??

Customer: replied 8 months ago.
No, exhaust is clear.
It takes full choke and throttle to start, even when warm, then I have to baby it to idle. If that means anything
Expert:  Curtis B. replied 8 months ago.

Does it still have the fuel solenoid in carb? Remove it and take the tip and spring out and try it without it.

Customer: replied 8 months ago.
It does have one. I heard it click when i disconnect it and plug it back in, but I didn't remove it. I guess the click could be just the solenoid, and not the mechanism itself, right?
Expert:  Curtis B. replied 8 months ago.

It must be working some, or there would be no fuel entering main jet, but for test, I would remove the inner works and try it. It is anti-backfire solenoid whose function is to keep engine from backfiring when key is shutoff hot. It does that by closing off the main jet when power is cut.

Customer: replied 8 months ago.
The mower is not here, 25 miles away. Do I need to get back with you tommorow ?
Expert:  Curtis B. replied 8 months ago.

Sure, you can, there will be link in your email to get back here.

Customer: replied 8 months ago.
Thanks, ***** ***** back to you tomorrow morning.
Expert:  Curtis B. replied 8 months ago.

OK> Good night.

Customer: replied 8 months ago.
Night
Expert:  Curtis B. replied 8 months ago.

Thanks