I have a 2005 4.3 Volvo. Per the service manual, the idle should be about 500 rpm in forward gear. The idle was running about 800 in neutral.
I tried Don's many suggestions and unhooked the throttle cable to see if that was the culprit - no luck. Even with the cable unhooked and the throttle pushed all the way forward, idle was still stuck at 800 in neutral.
There is a screw below and to the left of the throttle that I believe is the carb mixture screw. I turned it slowly and reduced the idle. However, as I reduce the idle with the screw, the engine runs progressively rough to the point that it is shaking really hard at 500 rpm. I ended up setting the screw at about 650 rpm with medium roughness on the engine and running the boat for a 1/2 day. With throttle the engine ran fine but it was still a little rough all day in neutral.
I assume that there are one or more different adjustments I need to make to the carb in addition to that screw to fine tune the carb mixture and smooth out the engine. I cannot tell from the service manual however what or where those adjustments are.
The engine and carb are both painted red. The adjustment screw is noticably not painted along with the throttle cable hookup. On the far left of the carb is a valve looking thing sticking out of the carb that is also not painted. Is that my other carb adjustment?
Any help in fine tuning the mixture would be greatly appreciated, including pictures
Thanks in advance!
I tried Don's many suggestions and unhooked the throttle cable to see if that was the culprit - no luck. Even with the cable unhooked and the throttle pushed all the way forward, idle was still stuck at 800 in neutral.
There is a screw below and to the left of the throttle that I believe is the carb mixture screw. I turned it slowly and reduced the idle. However, as I reduce the idle with the screw, the engine runs progressively rough to the point that it is shaking really hard at 500 rpm. I ended up setting the screw at about 650 rpm with medium roughness on the engine and running the boat for a 1/2 day. With throttle the engine ran fine but it was still a little rough all day in neutral.
I assume that there are one or more different adjustments I need to make to the carb in addition to that screw to fine tune the carb mixture and smooth out the engine. I cannot tell from the service manual however what or where those adjustments are.
The engine and carb are both painted red. The adjustment screw is noticably not painted along with the throttle cable hookup. On the far left of the carb is a valve looking thing sticking out of the carb that is also not painted. Is that my other carb adjustment?
Any help in fine tuning the mixture would be greatly appreciated, including pictures
Thanks in advance!