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cheken

Sunstar CH18 shuts off after heated

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cheken

Hello friends.

I have done some work on my Sunstar over the Winter and now I cannot seem to get her running well again. I pulled the motor to replace the stator and cleaned out all of the crud from the fins. After running until HOT, she will start to starve for fuel. I can run it back to the barn with the choke on. I am confident that it is in the fuel delivery system.

I have pulled the fuel solenoid (at the carb) because I though that this might be the problem. -The problem remains.

I have replaced the fuel line. I have installed (2 years ago) a DC fan to cool the block while running.

Has anyone experience this a similar before? Other forum entries speak of this but with float based carburetors. This CH18 Kohler does not have a float. Could it be the fuel pump?

I will check the carb needle conditions next. Can anyone make recommendations on the needle settings?

Thank you to all who might comment with a suggestion. sm01

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CarlH

I believe the Simplicity Sunstar CH18 does have a float although it seems to me the only way it would cause a lean mixture would be if it were set too low. I have not seen a horizontal crank V-twin Command that did not have a carb with a float. Do you have a Kohler spec # for this Command?

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Willy

If your fuel tank is higher then the carb try bypassing the fuel pump. At least you'll know if it's the pump,and if it runs good

just forget the pump.

Do you have spark when it stops?

If you have spark check your carb gasket, and the screws that

holds the to half's agather.

After it stops on you spray some card cleaner around the gasket,and see if it will fire.

Keep us posted and good luck.

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cheken

You are right CarlH and I am embarrassed to think that I would have a carb without a float bowl. B)B) Kohler M18S Spec 24594

Willy: I removed both the fuel pump and the carburetor. Both had loose screws so I thought that I had a eureka moment. I carefully disassembled the carb to for inspection. It was pretty clean. Reassembled everything, primed the carb and it still will only "run" with full choke and/or my hand over the carburetor inlet. I am going to try to gravity feed the carb to once again eliminate the fuel pump.

Yes I have a very strong spark under both hot and cold conditions.

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colincox1

I do not know if this will help but I have a sunstar to with the 20 hp Magnum engine and mine is always run Lean, I read some where that the carb has fixed jets and mixture settings cannot be change so all I do is just keep the choke out bit until it runs well.

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Willy

I had a problem like that with a Brigs one time.

I didn't feel like pulling the carb, so I removed the idle screw

and with the tube on my Carb spray can shoved it in the hole

and give it a good blast,stuck the needle valve back in and it's

still running. She must of had a slug in her belly.

It should be worth a try and it can't hurt anything.

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cheken

To all and thank you each for the contribution. It is/was always assumed to be a fuel delivery problem and that is correct. I had replaced all of the fuel lines and the problem existed. I removed and cleaned the carb -problem remained.. I removed and tested the fuel pump and it was delivering fuel -sort of.

When I removed it again to take it apart to check the bellows I noticed on of the internal valves was cock-eyed and both were loose.

Problem: The internal valves on the fuel pump were allowed to become loose when the pump body was warmed. This would interrupt the fuel flow and starve the motor. JB Weld is a temporary fix, a replacement fuel pump is on my search list.

One Sunstar is saved from being parted out. C

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