1976 Mercury 3 cyl. won't run in gear

[jakestevens]

Just bought a boat w/ a 1976 Mercury 3 cyl thunderbolt ignition 2 stroke. I was able to get it running with the flusher after replacing the primer bulb and the associated fuel line. After several successful starts on the flusher, I took it to the lake, and backed the trailer into the water. It cranked and cranked and never fired. I took it back home and connected it to the flusher, same problem. The next day I replaced the spark plugs and it started right up. Ok, I took it back to the water and it started on the trailer. I backed the boat off the trailer, spun around and put it in gear. The engine just seemed to fall on its face. The boat was moving forward but the engine was slowly dying. I had to pull the throttle to neutral so the engine wouldn't die.
I just bought the SELOC manual for this year model outboard and I'm studying on it.

I smelled of the fuel and it smelled fresh.

What does everyone think?

thank you..

 

[Chris1956]

Re: 1976 Mercury 3 cyl. won't run in gear

It is likely that you idle mixture is set too lean. You might open the top carb idle mixture screw 1/8 turn. Follow up with the bottom carb it that doesn't get it.

Also, what RPM does it idle on the muffs? It should be about 900-1100 RPM on the muffs, which will drop to 700-900 in the water in neutral.

 

[jakestevens]

Re: 1976 Mercury 3 cyl. won't run in gear

Thanks for the reply. I'm not sure of the RPM, the tach. is not operating, I'm working on that along with some wiring "nests" in the boat. The RPM does seem high though when at idle. And yes the RPM does decrease when it goes into gear.
Is there anything I can check, maybe the spark plugs, to see if the mixture is lean?

 

[Chris1956]

Re: 1976 Mercury 3 cyl. won't run in gear

It is hard to check the spark plugs to determine idle mixture. Merc Outboards need a rich enough idle mixture to accelerate properly, yet still idle acceptably.