Mercury 1150 - Not starting

[Coach Cal]

Hey guys, I'm having some problems with a 1977 Mercury 1150. I bought a boat with this engine on it recently. The boat set for about 8 yrs before I bought it. I pumped out the fuel tank and put fresh fuel in (50:1, put new plugs in, a new impeller and changed the lower end oil and it started. It ran pretty rough, so I had the carbs cleaned. In the process, new floats were put in all 3 carbs. After reassembling it, it won't start. It has good compression, timing is good, has spark and gets fuel. I'm stumped. Anyone have any ideas? Any help is appreciated

 

[Chris1956]

OK, a couple of things. Are you sure the carbs are filling with fuel? Pull the brass hex plugs over the main carb jets and see if fuel drips out when you prime it.

Are you choking the crap out of her? I do not think that motor can be flooded, so hold the choke closed and crank her until she fires, with the cold start all the way up.

Is the starter spinning fast enough to help the choke do it's thing?