Hi,

I had exactly the same problem with my webra91 abc. I could never run it rich. Fortunately, the engine was strong enough to bear all those overheating during test run.

I did not even think about expensive pump since fuel tank was already close enough. I thought it was carb. The carb probably had incomplete structure causing not enough fuel delivered.

As a work-around, I used YS check valve in the middle of back pressure line so that the pressure in the tank could make fuel flow actively. I also enlarged the nipple hole with a 2mm drill. The nipple attached on the muffler seemed to have too small hole. But you need to be careful not to break the nipple itself. Bingo! A lot better. No overheating any more and I could get the pick as I did on other engines.

However, still there is one problem. When you stop the engine after flight, the fuel still flows if left due to remaining pressure in the tank. you need to open back pressure immediately to release the pressure.

Hope it works in your case, too.

SeungWan
Seoul, Korea