I have a 2008 Mercury 20hp 4 stroke with electric start, short shaft. I bought it used and put it on a 14' Smokercraft aluminum boat. It has always been a difficult starter when cold, will take 10 seconds to crank and finally fire barely. The motor runs poorly when cold, it coughs, stumbles and sometimes quits it almost sounds like it is running on one cylinder. Once the motor has been brought up to operating temp, it runs perfectly wide open and starts perfectly afterwards. Idle's great when warm but low rpm it seems to vibrate the boat an awful lot though no matter if the engine is cold or not. I have changed the plugs, gapped them, new gas tank, line, ran several tanks of no ethanol fuel through it, no change. I am wondering if the Carb would be causing the problem on this?
Thanks
Thanks