85 Force difficult to start

I have an 84 Bayliner Trophy Fish and Ski, I have had it for approximately 5 years. The motor has become difficult to start recently. About two months ago I took the boat in for service, and it ran good for a while. Now it is difficult to start. When the ignition switch is pushed (choked) and turned it attempts to start, when the switch is released after several seconds the engine makes a whinning sound but doesn't start. I checked the plugs, they were black, but not burned, I replaced anyway. When pulling plugs noticed a rusty top on the top plug when I removed the spark plug wire. Cleaned the wire connector cap and put cap back on. Motor started the first time, as soon as the switch was turned. I tried it several times it started immediately each time. Went to the lake, last week it started at the dock, went out to the fishing spot, cut the motor fished for about an hour, tried to start the motor it was doing the same thing as before. Finally got motor to restart after about 5 miniutes of trying. Went to the house, frustrated. Removed and cleaned apparently clean plugs, engine fired immediately, waited an hour same problem as before. Removed, cleaned, and replaced plugs, again with apparently no oily residue on them motor started immediately. What should I check next? Any advice appreciated!

Re: 85 Force difficult to start

carburetors...... Ur engine is flooding after it sits.... Its pretty coming on our engines.. Some worst then the rest .... take your carbs off have them cleaned and needle and seats replaced or adjusted. check the float bowl... reassemble do link and sync procedure... then see how it goes...

Re: 85 Force difficult to start

Thanks for the advise, I will let you know how it goes!