omc gas problem?

[David Kraus]

I took me 1969 Uniflite out yesterday and after an hour or so the engine hesitated 2-3 three times and almost died. When I talked to my mechanic about this problem before he thought it may be water the gas. I filled up the tank and put gas treatment in but I still have the problem. One thing I did notice is that there isn't gas sitting in the secondary inline gas filter. Before it always seemed to be atleast half full of gas at all times. What should I be checking next?<br /><br />Also I'm hearing a slight vibration and whistling sound from the outdrive. Could this be related?