Mercury 9.8 1976 110 model question carb

decksitter

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May 11, 2009
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I recently purchased a Mercury 9.8 1976 110 motor. The person who sold it to me informed me the only problem is the carb will spit out gas at times when running. He put a new carb in last year and believes it needs adjustments. I have a couple questions. First can you adjust the carb so this doesn't happen, and roughly how many miles can I get out of 3 gallon tank pushing a 14 foot shallow john boat with about 450 pounds on board? Also is this a decent motor and is there anything I need to watch on it.

Thanks!
 

7920hpMercury

Petty Officer 2nd Class
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Mar 13, 2009
Messages
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Re: Mercury 9.8 1976 110 model question carb

This is a great little motor!

Never heard of spitting gas or maybe do not understand the problem.

I think I would get a Mercury or Seloc manual and pull the carb off and clean and rebuild it. Rebuild kits are available and a pretty easy job. A 76 9.8 carb should have a BB-1B,1C, 3A,3B,3C,6A,or 6C marking on the carb flange. 7.5 carb (incorrect) would have another BB number but looks identical.

Carb adjustment, slowly screw idle screw (with spring around it) clockwise with motor hot and in forward while idling until it dies or just starts to die. Then back the idle screw out about a 1-1/4 turn. You can also adjust the idle speed screw to about 750rpm. Do each a couple of times until you get it running and starting smooth.

Also I would check the compression, with the throttle wide open. Should be 100+ and each cylinder with say 10 to 15psi of each other. Also change the water pump every couple of years.

On fuel mileage, never checked it. I do know with a 450 load (light), the 9.8 will run a very long time on 3 gals of gas if it is running correctly.

Good luck!
 

cell

Petty Officer 1st Class
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Apr 16, 2009
Messages
208
Re: Mercury 9.8 1976 110 model question carb

Bad float needle,or a mis adjusted float will flood a carb.
 

decksitter

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May 11, 2009
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Re: Mercury 9.8 1976 110 model question carb

Thanks for the help and suggestions. I will give it a try over the weekend.
 
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