CC model B

[TaylorWhite]

I am having difficulty getting my model B engine to run. It ran for half a day early in the spring then died. I replaced the diaphragm on the fuel pump. It started and ran for a while, then stopped again. So, a few weeks later I put on a reconditioned fuel pump. It ran great for a day, then the next morning the engine died off of the dock again. So, the same symptoms as before. The boat turns over but does not start. Gas flows past the diaphragm. I know this because it comes out a bolt-valve across from the outflow of the pump. So, after I take off the valve, the manual pump can be engaged again. Gas comes out that valve. After putting the valve back in, it starts for a second or two. What should I try next? the carburetor? Does anyone have any ideas?