I have a 1977 Evinrude 70 that is hard to start when cold, or been sitting for a while. Starting with warmup lever up, choke, it coughs. I then have to crank & crank until eventually it catches, starter drops, out go again and it starts wtih a lot of smoke - like when you flood a car! Once started an it is warm it starts without a problem. It also runs well. Could this be float level, needle & seat or mixture or what?<br />Thanks