I have a 1992 force/merc. runs great but it I shut off the motor and restart it with 1-2 min it takes a long time to start. for instance I pull up to the dock back down the trailer and try to restart it cranks over forever untill I idle it up. but if Im out on the water shut it down, fish for 15 min and up it will start with just a bump of the key. has new plugs, primer ball is firm, thermostat, impeller replaced about 3 months ago carb is clean...any ides what to check and maybe how to check it