Nice job highlighting the tiny fuel passages! I have watched many RU-vid videos on this subject and this is the first time anybody made an effort to highlight these tiny idle fuel circuit passages. Being so small these are susceptible to contamination/blockage. The way you freeze the picture and highlight something in the frame and explain/offer advice is very effective. I have not seen anybody else use that technique on these type of DIY tutorial videos. Thank you!
Your engine does utilize the compartment for priming. It also houses the accelerator pump. The throttle lever pushes down on a white cap that covers the top of the plunger, which pushes the diaphragm and pumps a small amount of fuel into the carb when you open the throttle plate. You can see the linkage, a brass adjusting screw, the white cap and rubber boot which covers the plunger in the opening frame (2:21) of the engine. In the picture the long metal throttle linkage cuts right in front of the rubber boot. This is to enrich the mixture until the increasing vacuum can pull more fuel because when the throttle plate is opened air rushes in first (it has less mass) and the fuel lags slightly. When this diaphragm wears out and leaks the engine often bogs down for a bit when the throttle is opened quickly. I also wouldn't bother to open and clean it unless you are having this issue or the housing is leaking fuel (the diaphragm also serves as a gasket). The engines that have a small primer bulb also use this component to pump a small amount of fuel for starting. Thanks for the video, the freeze frame and red circles are great.
Thank you for this video. Tons of great info without a lot of b.s. which seems so prevalent with guys making youtube vids. Gave me lots of confidence before tackling my 9.9 carb. Best wishes and thanks again from Sakinaw lake B.C.
I appreciate his video I just wanted to know was it 8 or 10 mm. I understand the gaskets in the air fuel mixture and all that depends on the year I prefer 2-stroke I don't know about everybody else out there give me a thumbs up. If you would rather have a two-stroke
Great video. I have a 1993 15Hp so hope the carb is similar. I assume you replaced the gasket to fix your idle problem. I'm going to try chemical cleaning first. If I have no success then I will try and pull it apart. happy fishing from New Zealand.
