Help with Yamaha Pro 50

[yamahahelp]

HI,
Need help with a Yamaha Pro 50 LG. It's on an 18 ft pontoon. I just bought it and it ran fine the first time out. I don't know what year it is. The no. is:
6H5 L 503673. Any help on year would be great. While we had it out the first time it was running at 25 MPH with no problem and then all of a sudden it went to running at only 10MPH and that's all it will do now. Any ideas on where to start? This is our first boat and outboard. Thanks in advance for any help.

 

[JUSTINTIME]

Re: Help with Yamaha Pro 50

what about a model number?
check oil level
check for water in gas

 

[yamahahelp]

Re: Help with Yamaha Pro 50

No. 6H5 L 503673
Have checked oil and it's full.
How can we check for water in gas? Sorry, newby