Yamaha Cuts Out with Increased Speed

[TheLighthouse]

Hi,

I guess this may be a common problem, and I would have looked at the Knowledge Base, but the link seems to be broken.

My Yamaha 2-Stroke 4HP has always been slightly tempremental, but I still enjoy using it. However, today I took it out and it consistently cut out at higher revs. It allowed a small time at high revs before cutting out. I could run it as long as I wished at low revs.

I have been told it may something to do with the fuel jets, but I wondered if any of you might have a better idea? I am not currently using an external fuel tank.

Thanks in advance!

[Ken]

Scottie,
If your spark plug is at least a year old, replace it.
If new plug makes no difference, then you probably
need to work on the carb. If that motor was allowed to set up for more than a month without being run, and the storage procedure in the owner's manual was not followed, then the carb could well be clogged up. You could try a shock treatment with RingFree or SeaFoam - might help.
If not, then carb needs to be torn down and cleaned.
Also, you should check the fuel filter before doing any of the above - maybe just clogged up.
Also, check the fuel tank vent - may be clogged up and not allowing higher fuel flow because of vacuum.
Good luck [img]smile.gif[/img] ,
Ken K

[TheLighthouse]

Hi,

Thanks for the reply - will go through the steps you've outlined. The engine was set up and not in use for a number of months, but I have used it a couple of times recently without a problem - it just started playing up.

Will let you know how I get on!

Cheers.

[floridaflatbed]

I had sort of the same problem.

I think the problem shows up later, maybe because the sediment sticks to the bottom of the bowl, and gradually breaks loose, and causes a problem.

Thats why the engine operates fine the first couple of times after sitting.