9.9 Idle Screw Adjustment E10RCTR

My 9.9 starts and runs well but the low speed idle screw on the side of the motor cannot be adjusted to reach the linkage to prevent me from throttling to low when shifting. Seems there's not enough travel in the screw adjustment. The throttle appears to be set correctly, for example, it starts when set to start. The gear teeth on the throttle arm and motor are aligned. I would say that the carb cam follower is pretty far from the timing cam at low speed. Any ideas? Thanks Nick

How long have you owned the motor ?------Can you turn that knob on the side or is it seized ?--------Is the motor in good condition and running on both cylinders ?----And there should be clearance between the follower and cam at idle.-----At idle the throttle plate MUST be closed.

Just starting up after 8 months winterized. Ran fine last year. Working on a separate problem where it won't idle for a long time. Probably a carb/fuel pump issue working on that separately. Runs longer in my workshop with the fuel tank above them motor, shorter when the tank is on the floor. Just learning about these great motors and noticed that the mechanical stop cannot reach the linkage stop even fully screwed in (not seized). I can turn the throttle low enough to stop the motor. Yes, throttle plate closed at idle.

Bring it over.-----I have a couple of the 83 models for parts / rebuild.------Should be easy to figure out why it won't adjust to the stop !

Thanks, where are you? Nick

If tank works by siphon but not providing enough fuel on suction, it is likely a fuel pump. Could be your idle adjustment itself is okay but there is too much play up above between the vertical throttle rod and the stator. The carb should be closed at idle position and the stator ramp just ready to, and not quite touching the carb roller assembly. Note: Racers description. Try adjusting your low speed needle to bring idle up. Perhaps it's running too rich, which would bring idle much lower than it should be when stator is in aforementioned position. What is your compression #'s? Low compression means unhealthy motor, low power, poor starting, poor idle. How is lower unit bearings, etc?.....it's lube condition my help tell the story....If motor doesn't turn very easily with spark plugs out, perhaps there is drag down there.

I ended up rebuilding the carb. There were 2 problems. First, the float needle had a rubber tip that was stuck in the seat preventing fuel from entering the bowl. The rubber tip broke when i pulled it out. The new needle is all metal. Secondly, the low speed idle screw was out of adjustment and it's gasket broke up when I was adjusting it. Replaced the gasket and got the needle out to the 1.5 turn range of seated and tweaked it while running. Now the throttle can twist down far enough to get in range of the mechanical low idle speed adjuster stop. I also happened to install a new fuel pump after I messed mine up during my investigation. The new Sierra fuel pump is a beautiful thing, appears better than original, hoping. BTW compression is 135 in top and bottom.

New plugs, new fuel, the engine ran for 30 minutes at idle in the tank with no sign of trouble.

Thanks to all!

Excellent compression. These tiny fuel pumps can be tricky to overhaul. Good job. Did you notice how idle speed increases as you bring in the needle?

It was very rewarding to spend the time and money and actually get results exactly as advised. I was lucky to start with a good engine. Believe it or not, I started with a 9.9 Sailmaster that a friend gave me that he gave up on. I wanted to learn on another motor before tinkering with my good motor. After 20 hours of finding almost everything you could think of backwards, broken or upside down, I actually got that motor to purr like a kitten.