18 Hp Mercury Carb is Flooding

[kwebb]

I have an 18hp Mercury that I believe is flooding. Clened and rebuilt the carb with a new diaphragm and gasket set, put new plugs in it and it still ran like it is flooded. pinched of the hose going to the carb at full throttle and after 10 seconds or so it will rev at high speed for about 4 seconds until it dies. Jet screw has little affect on the performance of the motor, so I took the carb in to a boat shop and had them clean and rebuild it. they did not find anything wrong with it, put it back on the motor and it still runs the same way

Any suggestions



thanks

k

 

[oldman570]

Re: 18 Hp Mercury Carb is Flooding

Check the float setting and replace the inlet needle if it is worn. Could also be a plugged low speed air passage also. Idle setting should be 1 1/2 turns out from lightly seated on jet. Or find another boat shop that will get the job done.
Oldman570

 

[kwebb]

Re: 18 Hp Mercury Carb is Flooding

i had the float set up so tight that it would not let any fuel in, and then backed it off some. one thing I noticed today was that there was a lot of fuel misting up into the throat of the carb where the long skinny tube came up through the larger tube...both comming up from the float box. is that normal?

kw

 

[oldman570]

Re: 18 Hp Mercury Carb is Flooding

Yes, that is how the gas gets to the motor. By pinching off the hose to the carb you have shut the flow of gas to the carb off. The jet screw is for the idle only as the high speed jet is not adjustable.