Koehler 12.5 Fuel problems.


Old 07-09-15, 12:35 PM
Thread Starter
Join Date: Jul 2015
Location: canada
Posts: 1
Koehler 12.5 Fuel problems.

Hello there.
i have been reading your threads and solved a few of the issues with my newly purchased very well used Club Cadet with 12.5 Command Koehler engine.
I solved all the electrical through your past threads.Thank you for that.
Now that i have the starter and all the wiring straightened out. It runs like a dream. The only problem is on the initial start.
I have to squirt a little quick start in the carb to start. i know thats not good. Thats why im here. once it starts, it runs beautifully and purrs at all Rpms.
I took the carburetor off and gave a thorough cleaning of all ports with carb cleaner and air. It runs great but wont start even with the choke on.
It has a fuel pump which i removed, inspected and replaced. It looked good and the diaphram looks ok, but its pretty old and i dont know what OK is. It has no holes and the valves seem to work.
I took the fuel line off and blew into the tank until i heard clear bubbling in the fuel tank. The fuel cap was off so no venting issues.
What i did witness was that the inline fuel filter in the inlet side is clear. I could barely see any fuel running through the filter even when running at full speed.
Again the engine runs good, it just seems that it doesnt have any fuel for starting. My guess is that the fuel pump diaphram may be weak or the pump internal check valves dont work like i think that they do, because i cant really see any fuel running through the filter while its running. There must be fuel or it wouldnt run. even after warm up. As soon a shut down it wont start up until Quickstart, then it purrs again.
Any ideas.
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Old 07-09-15, 03:29 PM
Join Date: May 2006
Location: Iowa!!!!!
Posts: 3,728
The fuel for the starting would come from a reservoir in the carburetor. If it's a float type that would be the float bowl. Make sure it has fuel in it before starting the engine. If not, look at the condition of the fuel lines, flow from the tank, and any blockages that may affect the supply of fuel. From there, if a pulse driven pump, check the vacuum pulse feed from the crankcase going to the pump. If that is good, think about putting a kit in the pump or replacing it..

The filter is typically on the draw side of the pump so you wouldn't see a lot of fuel movement in the line filter. If the filter was between the pump and carburetor it would show more fuel since it would be forced to fill and the volume would be held in check with the valves in the pump.

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