Air bubble in fuel tank?

[ruperthebare]

Hi,
I have an older Castel garden r/o with a Kohler Courage 15hp. I have had problems with carb etc (see my other posts) but it is now running quite well, fingers crossed. I thought it was a bit juicy, approx 1 uk gallon per 2.5 hours work, so I weakened the mixture right off. Then under load and uphill it would peter out occasionally. Also at this time I noticed a bubble or more appearing in the petrol tank from the outlet pipe (to carb), so air. I have now riched (opened the jet) the mixture right up and the problem of petering out has largely stopped, just one or two suggestions. The bubble is still appearing in the tank. One of the studs holding the carb on is turning and wont tighten fully, but I would have thought tight enough. Any suggestions/ thoughts?
Regards, Rupert

 

[Tiger Small Engine]

Hi,
I have an older Castel garden r/o with a Kohler Courage 15hp. I have had problems with carb etc (see my other posts) but it is now running quite well, fingers crossed. I thought it was a bit juicy, approx 1 uk gallon per 2.5 hours work, so I weakened the mixture right off. Then under load and uphill it would peter out occasionally. Also at this time I noticed a bubble or more appearing in the petrol tank from the outlet pipe (to carb), so air. I have now riched (opened the jet) the mixture right up and the problem of petering out has largely stopped, just one or two suggestions. The bubble is still appearing in the tank. One of the studs holding the carb on is turning and wont tighten fully, but I would have thought tight enough. Any suggestions/ thoughts?
Regards, Rupert

The loose carburetor stud is stripped and will not work. Possible air leak in intake therefore throwing off air/fuel mixture. Spray carburetor cleaner around intake while engine is running (carefully) and listen for change in Rpm’s, indicating an air leak.

 

[ILENGINE]

The loose carburetor stud is stripped and will not work. Possible air leak in intake therefore throwing off air/fuel mixture. Spray carburetor cleaner around intake while engine is running (carefully) and listen for change in Rpm’s, indicating an air leak.

Keep in mind that the Courage single only uses 1 threaded stud. The left stud is threaded into the head. The right stud is actually a square headed bolt that mates into the back side of the plastic carb adapter plate. And the bolt that connects the ground wire for the fuel solenoid is the second bolt that holds the plastic adapter in place. And to @ruperthebare I am not sure I understand your air bubble in tank unless you are referring to the fuel filter, which you can ignore any air space in there since it is actually filled with gas vapor that goes back to liquid when it goes back into the fuel line.

 

[StarTech]

There is one other possible problem that I have seen with these. And that is carburetor fuel bowl and fuel line to the carburetor is super heating and the fuel is boiling creating a vapor lock in the fuel filter. Many of the older Courage engines had this problem so Kohler developed a heat shield for the carburetor.

The root source of the problem was the use of a winter blend of fuel during the Spring and early Summer months before the fuel vendors had updated their fuel blends.

Kinda easy to see the problem by looking at the clear filter and see bubbling going on after the engine shut down. Usually it is gravity fed as fuel pump tends to over ride the vapor lock but not always.

Even JD had problem with one mower where they shielded the whole fuel line.

 

[ruperthebare]

thanks all, will take a closer look at the fuel filter​