Too rich at idle

[dacton]

Hi people. I have a 1988 merc 15 HP. The problem seems to be excess fuel.
I found it not idleing smoothly and smokeing. Adjusting mixture screws did not help. If I tilt the motor up it idles much better but not perfect. Run it at planeing speed it works perfect. I replaced the float and needle, but the seat is not replaceable. The reed valves and compression are ok. It didn,t cure the problem.
I then installed a fuel pump kit. It still has the problem. My question now is how do you recondition the seat, and could there be another area I should investigate.
The water is still too hard to use it in Canada, but I am getting ready for the thaw.
Thanks for your thoughts.

 

[Barnacle_Bill]

Re: Too rich at idle

Did you adjust the new float properly? Not much you can do with the seats except make sure they are clean.

 

[Ady B]

Re: Too rich at idle

Hi dacton, I had a similar problem with my engine recently. It turned out to be a split fuel pump diaphragm. Might be worth another look. Ady B

 

[dacton]

Re: Too rich at idle

I have in fact tried lowering the float, it did not help the idle. It did not work well at high speed. I raised it again. Is there a tool that cleans and reshapes the seat back to like new conditon?

 

[dacton]

Re: Too rich at idle

Ady B, I will recheck the fuel pump when I have it apart . It,s too cold at this point to do anything but research.

 

[hkeiner]

Re: Too rich at idle

Did you soak the carb in a gallon can of carb cleaner and blow all the internal passageways out with compressed air when you had it apart? Spraying the carb with only carb cleaner spray is often not sufficient to clean a gummed up carb properly. I had a similar problem with my motor and cleaning the low speed idle air passageways seemed to improve things a lot. It is possible that a restricted idle air passageway will cause the motor to run too rich at idle.

The below troubleshooting guide lists some more things that you can check.

 

[dacton]

Re: Too rich at idle

Did you soak the carb in a gallon can of carb cleaner and blow all the internal passageways out with compressed air when you had it apart? Spraying the carb with only carb cleaner spray is often not sufficient to clean a gummed up carb properly. I had a similar problem with my motor and cleaning the low speed idle air passageways seemed to improve things a lot. It is possible that a restricted idle air passageway will cause the motor to run too rich at idle.

The below troubleshooting guide lists some more things that you can check.

I disassembled the carb many times looking at all circuits that could supply fuel to the intake. I was checking the primer circuit and found the check ball was incased in the spring, it looked ok to me as I am a rooky on carbs. I pushed the ball back out of the spring, put er together again. It is now running quite satisfactorily. I wonder how it got that way to begin?