Just for giggles, check the fuel lines on the engine carefully. There is a filter on the engine after the Racor. The inlet and return can be reversed and the engine would still run. But, it will get starved for fuel after a while. A small engine like that will go for quite a while. I have done this, that's why I know. I did it on a 44 HP Yanmar and couldn't figure out why I couldn't run for more than 20 minutes or so. I actually installed an electric fuel pump, thinking it was the mechanical pump that was tired. Then a mechanic friend of mine was on my boat and was looking at it. In about 30 seconds, he switched the fuel lines top and bottom and all was right with the world. Just a thought. On mine, the intake went to the bottom and the return was on top. To me, I just hooked it up the way I thought it should go. Intake at the top, return at the bottom.