2002 25HP Merc Wonbt Idle

" It won't run without hav

" It won't run without having the choke about 3/4 to 7/8 on. It will work at 90% performance if choke is left around the 3/4 setting at speed. It appears to be carburetion but I can't see any blockage.
Timing/spark and compression (112) all OK. I think a brass plug or jet might have fallen out of the carb. There are two open holes into the bowl and one open hole behind the choke flap, the other one is on the open face is plugged. This is like a low speed jetting problem but there doesn't seem to be a low speed jet. Any experience out there? "

"Jeff,

I have seen similar

"Jeff,

I have seen similar problems on these engines. First, you have to remove the carb and make sure the main jet is clean, along with everything else.

These carbs have a throttle valve that moves up and down as you work the throttle lever. This is the cylindrical part that you can see when you look into the carb bore. It has a needle that hangs down into the main horn. As the cylinder rises up, it allows more air into the intake, and the needle is drawn up also, allowing more fuel to come up through the horn.

The position of the needle in the cylinder, determines the mixture throughout the operating range of the engine. In order to adjust the mixture, you have to take that needle out of the cylinder. You will see a circlip which goes around the needle. It locks into a groove on the needle. By changing the groove that the clip is in you can change the mixture. There should be three grooves on the needle. The factory setting is in the center groove. I would suggest that if cleaning the carb does not remedy the situation, that you change the circlip to the lower groove on the needle. This will richen the mixture a bit which usually solves this problem.

"