Yamaha carb flooding - The Hull Truth

shamdiesel · 06-22-2009, 09:31 AM

I Have a 2001 15 hp Yamaha 4stroke. When I prime it with the gas bulb gas floods out of the top of the carb. This happens when the motor sets for a week or two. I have taken the carb off and put in a new float and needle valve(carb kit). It works fine until it sets for a week or two then the same problem. The gas is always stablized and fresh. Why wont the valve seal? Is there an upgrade for this carb? Thank you in advance.

A1 Outboard · 06-23-2009, 02:02 PM

You didn't mention if you used genuine Yamaha parts. Some aftermarket parts are not always satifactory. You have to also be sure that you are not over pressuring the carb. It is easy to pump as much as 50 psi with the primer bulb. Change the engine fuel filter to be sure no piece of debris is holding th needle open.

shamdiesel · 06-24-2009, 07:38 AM

The carb kit was a Yamaha, and a new filter was installed. The gas bulb never got hard when it was pressed, about three times and the gas just flows out of the top of the carb. When this happens I remove the carb turn it upside down a few times and it works fine until it sets for a while. The float is new and is not sticking or touching the carb body.

cjldad · 06-30-2009, 08:55 AM

I too have the exact sqame problem.. It ran fine all season last year, but I took the carb off to clean this year and it has done it ever since.. Comes out the top plate of the carb.. I usually just pump once and tap on the side of the carb, then continue pumping.. I've been trying to figure out if it is hitting the side of the float bowl or why it is sticking and I cannot figure it out! I cannot get the carb apart easily enough to catch it in the stuck position.. It is just so weird.. You would think it would move around a good bit while I trailer it to the river so it wouldn't be stuck.. Once it is cleared up, all is well.. Please let me know if you figure it out!!!

A1 Outboard · 06-30-2009, 09:15 AM

Check the float level. Turn the carb upside down, the float should be parallel to the surface where the bowl attaches. Carefully bend the stop to correct the level.

cjldad · 06-30-2009, 09:19 AM

There is no float adjustments on these floats.. It is an all plastic design.. Either way, the float is level and everything runs great once it is unstuck...

Also, once it is unstuck.. I can blow in the fuel line and feel the float open and close when I turn the carb over...

A1 Outboard · 07-06-2009, 04:24 AM

It sounds like you are getting debris in the fuel. See your dealer about installing a small water separating fuel filter in the fuel line. It may solve the problem. Your dealer can also request a field service person to have alook at your problem when he is in the area.