Gas Leak from Upper Carb on 1971 Mercury 500 50hp

skaggst

Seaman Apprentice
Joined
Apr 8, 2013
Messages
39
The saga continues...had the merc on the lake yesterday and after running it for about 20min noticed about a pint of gas in the bottom of the boat. We loaded it up and pulled the covers and we noticed a drip from the top carb (near the front) when I pumped the bubble on the gas tank, when I tipped the engine up. When we were running the motor I had to continually pump the bubble as the engine would start to stall from lack of fuel. Today I tipped the motor up, opened the throttle (motor not running LOL) and pumped the bubble, saw a steady stream of gas running out of the front of the top carb. These carbs were rebuilt earlier this summer by a mechanic. My initial thought is the front plug is loose or missing. Can't really see it without doing some major tear down. Thoughts? Any help would be appreciated, needless to say I won't run the motor until we fix the leak. Might be a large mushroom cloud on the lake.
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
27,158
Re: Gas Leak from Upper Carb on 1971 Mercury 500 50hp

it is very unusual for a carb leak to drip into the boat. They are made to drain into the lake. Sometimes carb floats stick. Check it again later, as it may have come unstuck. If not you need to pull the carb cover and see what is going on. Could be dirt in inlet needle seat.
 
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