Trouble starting again after first startup 50hp Mercury

I have a 50 hp Mercury OB 2-stroke, mid-seventies vintage. When I first start it up it runs fine until I stop the engine. Second start and each time afterwards, it has trouble starting. After choking, it will start but put into gear, it dies, again and again. 10 - 15 tries to get underway. Fuel line is clear, no blockage in fuel filter, bulb is hard. Fuel is mixed properly. This engine has been rebuilt but I do not know the extent of the rebuild. I have owned it about 2 months. I have to believe this may be operator error as I had a 70 hp Johnson that behaved exactly the same way. Any suggestions?

Re: Trouble starting again after first startup

First, you may have better luck posting an issue with a Mercury outboard in the Merc forum. The folks here are great with general issues, and OMC power in particular, Not too many are intimately familiar with Mercury products.

Second, it sounds like the engine may be heat soaked. Make sure you have it propped to run near the red line at full throttle. A fresh water pump may be a good idea, as well as checking or replacing the thermostat. Not sure if that model motor has a vapor seperator, but if it's not functioning properly that could contribute to the issue.

Re: Trouble starting again after first startup

Hijwats1.I have had a problem like that with an Evinrude and found that sum previous owner had stripped the thread on one spark plug and fitted a coil which had became thread damaged.also found that it would not idle.After engine heated not sure if loosing compression or sucking too much air or both.I don't know much about engines this my experience.

Re: Trouble starting again after first startup

Mine did that too. I bypassed the in-line fuel canister that was installed on the boat, and never had another problem. I would try a new fuel line assembly, and a fresh 6 gallon can of fuel and see if your problems go away.