1988 35hp mercury side bowl carb

[dale 63]

Used but new to me boat with 35 hp merc.I am totally lost on how to work on a boat engine.The third time I had it out I went 3 miles up river and noticed a little gas leaking. After starting and repositioning to anchor 2-3 times I noticed much more gas.Trying to start after that was futile and gas was pouring out.We trolled back and at home I saw where the gas was coming from. It's a side bowl carb and near the top is a brass screw with a hole in the center.The gas atreams out of there when I hook the gas line up. I suspect it is an overflow screw/hole and the float is stuck.Anyone have any idea what the problem is and how to fix it?

 

[Maxz695]

Re: 1988 35hp mercury side bowl carb

The needle and seats are not closing or there is a stuck float that brass screw is the overflow to let you know somehting is wrong in the carb. I would take the carb apart and rebuild it

 

[jslu]

Re: 1988 35hp mercury side bowl carb

dale 63
I had a very similar problem with the same type of engine and carb. After removing the carb from the engine (good luck removing the mounting nut nearest the side bowl, you need a very thin wall socket), I discovered a very tiny shard of plastic ( I almost didn't see it) from a newly installed fuel filter had lodged between the needle and seat resulting in a fuel flooding condition.After re assembly ,the engine ran perfect again. i thought that is was ironic that my last line of defense to guarantee filtered fuel to the carb was my demise.

John

The needle and seats are not closing or there is a stuck float that brass screw is the overflow to let you know somehting is wrong in the carb. I would take the carb apart and rebuild it

 

[dale 63]

Re: 1988 35hp mercury side bowl carb

Thanks guys. I have been on duty and have'nt had the chance to work on it at all.I did however after posting here had another look at it. What I am guessing/hoping is that I found the problem,please reply if you think this is right. The lower screw in the fuel pump was backed all the way out and the lower part of the engine case was all that was keeping it from falling completely out.I hand tightened the screw and hooked the gas up. No gas poured from the overflow as before. Do you think somehow the pump was sucking air and somehow was causing the problem or, do you still think it's a carb problem? BTW- I inspected the motor thoroughly and know for sure the screw was not backed out before this problem occured.

 

[Chris1956]

Re: 1988 35hp mercury side bowl carb

Likely a carb problem. The brass backdraft jet is not a fuel overflow, but if the carb floods, fuel will pour out of it. Inspect the float. The hard plastic floats can crack. The inlet needles and seats can lose their neopreme coating and not seal well. Dirt can get into the seats and cause the carb to flood. Floats can stick causing flooding as well.