Engines do not flood due to fuel tank pressure UNLESS they are in a tilt position which changes the float level in the carburetor.

If the engine is sitting in a normal RUN position and floods, you need to re-work the carburetor... new float needle valve, re-set the float.

Also, if the fuel pump diaphragm is cracked, that would allow fuel to flow through it directly into the cylinders.

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(Carburetor Float Setting)
(J. Reeves)

With the carburetor body held upside down, the float being viewed from the side, adjust the float so that the free end of the float (the end opposite the hinge pin) is ever so slightly higher (just ever so slightly off level) than the other end. And when viewed from the end, make sure it is not ****ed.
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(Fuel Pump Diaphragm Test)
(Two Hose Type Only)
(J. Reeves)

Note: This pertains only to the regular Two Hose type fuel pumps.

Leave the hoses attached to the fuel pump. Remove only the two screws that attach the fuel pump to the powerhead. Re-insert those two screws and install a nut to each of them so that the fuel pump is securely clamped together. With the fuel line attached to the engine, pump the primer bulb while observing the pressure/vacuum operating hole on the back side of the fuel pump. Should any fuel leak out that hole, the diaphragm is faulty.

If the diaphragm is faulty, the fuel pump will require rebuilding or replacing. Note that repair kits are not available for all fuel pumps, in which case replacing the pump would be necessary.

9 1/2 Evinrude flooding

Thank you Joe - appreciate the help. One item I neglected to mention is the very same thing happened with a similar era Johnson motor - with a newly rebuilt carb. The only common denominators are the boat, fuel tank and fuel line. Seems odd both motors would have the same carburetor float issue. It's a small 12 ft rowboat - could it be pitched enough with me sitting in the back to cause the issue? Mike