Engine only runs at half-choke.

[sscotsman 186]

So up until today the engine/carb has been running normally:

Put choke "on" to start, start engine, move choke to "off" or "open" position..all is well.

 

Original 1964 Kohler K181 engine on a 1964 864 Wheel Horse.

 

This afternoon I went to mow the lawn..

Engine would only stay running at "half choke"..

If I tried to put it on "no choke" it would stall out..

I know this means something, but I dont know what..

diagnostic please?

thanks,

Scot

[oldblue1993 98]

have you put a fuel filter on it? If not chances are some crap got into carb, somtimes it will just run its course other times may need to drop bowl and see whats inside. Just my two cents.

[buckrancher 2,694]

sounds like water or dirt in the carb to me

 

brian

[MalMac 1,332]

I agree with all the replies. I just went through this. Was out mowing when it started acting up, had to pull the choke out to get it back to the barn. Took the carb off and pulled the bowl off and there sure enough was a bunch of junk. Cleaned the carb good, put new fuel filter on and back at it.

[Martin 2,133]

yep, agree with all of above......

 

the reason why the engine 'needs' the choke partly out to run ok is its lacking in fuel to run properly. its getting enough air, but in order to run right the engine needs the right amount of fuel/air. (14.7 to 1 to be technically correct) although slightly richer or leaner may be needed.......

now because you have a restriction in the fuel side of things, either the line in to the carb or inside the carb itself (most likely), the engine 'needs' more fuel to compensate. its getting that compensation by choking the engine slightly, closing off air delivery somewhat, which also causes more suction within the carb itself and therefore more fuel to air is being drawn into the engine.

 

in short, if you need to choke the engine to get it to run ok, you are lacking the normal amount of fuel to air ratio. the choke function is correcting this lack of fuel to air somewhat.....

 

i would bet that your main mixture needle is blocked because you are drawing junk from the fuel bowl in the carb. now i say junk, it could be something very small, doesnt take much to block those small holes in the passages. a fuel filter between the pump and carb is always your best friend. (unless its blocked as well).....

Edited August 29, 2013 by Martin

[CNCJerry 5]

I agree with all the above as well.

I just went through this with my WH this spring, it would only run with the choke full on. I pulled the air filter off pulled the main needle and blasted the carb with carb cleaner and few shots from my air compressor, put it all back together and runs perfect. My float bowl only had a very small amount of dirt in it, but it only takes one small piece of dirt to clog the very tiny holes in the carb.

[oldblue1993 98]

I use times like this as an excuse to my wife to put some money into mine, It may be a free fix but you may want to put new lines and a fuel filter in her "if they are old".  Just a Thought.

[sscotsman 186]

Thanks for the info guys! much appreciated..

looks like a carb cleanout, and installing a fuel filter is in order!

glad its a (relatively) easy fix..

thanks, I will let you know how it goes!

Scot

[953 nut 57,877]

I would start by using some Seafoam Carb spray into the carb while it is running, this has cleared up problems for me on a couple of ocassions. If you are using E10 gas you may also want to replace the fuel lines while you are replacing the filter. That junk will cause problems! Go to buyrealgas.com to find a dealer in your area that sells ethanol free gas, it will cost a bit more but save you a ton of problems.

 

Good luck and keep us posted.