Thread: yamaha outboard

I have never had a Yamaha so I know nothing about them I have a 1996 60hp took it out last Friday for first time I fired right up ran it up river about 300 yards then went down stream about 500yards running great had my buddy park truck picked him up headed down stream ran about 100yard it died would not crank checked the fuel line bubble it was soft pumped it up fired right up went another 100yards died again check the vent knob on tank opened it up pumped bulb up fired right up another 100yards it died bulb soft tightened the vent valve as tight as I could pump bulb up it fired up and ran fine all-night is that the way Yamaha's run with the vent closed

No...you pump up the bulb to send gas up to the float bowl in the carb. Once the float gets to the top of its stroke it shuts off the valve attached to it. That's why it gets hard...the valve is shut and you can't pump anymore. The primer bulb has a check valve in it so it shuts and everything is held full of gas. If it does not get hard then the valve on the carb bowl is not shutting and if you keep pumping gas will spill out the carb inlet.

Now...when the engine starts the fuel pump will draw gas from the tank...the bulb should not be hard... as the pump is pulling gas from the tank the pressure you built by pumping and the float valve and check valve held...are now open and allowing gas to flow and the pressure on the fuel line will drop.

You probably have some debris or just some gunk in the float valve or fuel pump or carb jets or a little of both. Depending on how old your fuel lines are and how long the gas has been sitting...you may need to replace some stuff or at the very least clean it all out.

Get some Sea Foam and fresh gas and then take that thing out and run the heck out of it. If you're lucky it may just dissolve anything giving you problems and it will help decarb the plugs,rings and pistons. Yamaha ring free is good too.

If still have problem you may have to ..clean out tank ...replace fuel lines...maybe primer bulb...fuel pump kit...fuel lines under cowling..clean carb bowl and jets...maybe need carb kit but honestly most of the time the parts are okay...generally the gaskets will even stay together. If the gas is good...the lines are not breaking down...then clean the carb and inlet screen on the fuel pump and see how it does.

If I have an older motor and I want to get to good reliability I am basically going to go systematically from the tank pickup tube to carb outlet..... cleaning....replacing as needed.

The kit parts if needed are really not all that expensive generally and if you have a little mechanical aptitude and some patience you can pull it off. Especially with a manual if you want to buy one...

I have never worked on your specific motor but if its a 2 stroke carbureted model they all work about the same.

I am talking about the vent on the gas tank motor will only run a short time with this vent open it runs fine with this vent closed

I understand but the vent has to be open to allow air to come in to replace the gas being drawn out.

You must have an air leak somewhere letting air in. That's another thing....any air leaks in the fuel line anywhere will cause problems

The point I was trying to make was it can often be more than one thing...and also on a motor that old unless someone has been doing some things over time....it's usually time to go all through it and then you're good to go for a while without some other thing cropping up that was borderline working anyway. So you fix a main problem and clear out other potential problems at the same time.

I am not a certified mechanic...just fixed a few motors over the years. Some certified mechanic comes on here feel free to disregard anything I have said.

It's all pretty common sense though once you understand how these basic single fuel line...carbureted... fuel pump that works on engine stroke...outboards work. There may be something different about yours I am not aware of...let's see if someone can add something.

Or the exact model and look at the parts break down will help figure it out.

You can always post on I-boats too.

You took it out a week ago. How long before that was it ran?

it had been out in april and had been run on a water hose every month since i baught it in july

If you are saying that it runs fine with the fuel tank vent closed and keeps dying with it open, that is strange and doesn't make much sense to me.

These types of situations are why I like to put a clear fuel filter on the line between the fuel pump and the carburetor. If the filter is drained of fuel when issues arise then you know that the problem is upstream of the carburetor (likely the fuel pump) and if it is full then you know that the carburetor inlet needle is sticking and not allowing the bowl to refill with fuel.