I have a 78to 83ish merc 90 stack 6, after it sets all week and I try and start it , it turns over and over for about 3to5 min(seems like). I pump the bulb good and tight ,the bat. is fine I choke it and I've checked my choke flaps. After it starts ,it fires right up the rest of the day.What else can I check, I'm afraid if I continue like this I'll burn my starter and hurt my fly wheel. Thanks