I’ve have two gas tank caps (doors) for my black tank Martin 40.
Turning the vent screw in the cap doesn’t seem to effect how much air I can blow thru from below.
Is it supposed to seal??
Phil, I checked my Martin 45, and yes it does seal when the vent screw is fully closed. The 45 is the same motor, but has the twist grip throttle control. I would suggest contacting club member Russ Larson [Larson Outboard Service] for the parts you need.