Yamaha F15 key switch?

[openwide]

I have a 2002 Yamaha 15hp 4-stroke on my tender with a remote steering station and electric key start. The engine will start normally over 90% of the time, but just when you think the issue is gone, it will randomly pop up again. The problem is that when you turn the key to start it will just barely bump the engine over and then stop just as if you had a weak battery. Usually within 10 tries it will turn over normally with a strong cranking speed. It has never failed to start, it just may take multiple attempts. When the problem first occured, I replaced the battery assuming that it was the issue. I believe have checked and cleaned all the electrical connections on the battery and engine, so I'm guessing that it is possibly the key switch or some other connection in the control box. Any thoughts would be appreciated before I consider opening it up for a winter project.

Thanks - Open Wide

 

[Capt Ken]

Re: Yamaha F15 key switch?

If the solenoid is clicking everytime you turn the key, then the switch is fine. You may have solenoid that has a bad spot on the contacts.

 

[99yam40]

Re: Yamaha F15 key switch?

Could be a bad cable or connection also, need to put a volt meter on different connections under load ( voltage drop test) when the problem shows up to determine if it is the start solenoid or a cable or connection

 

[openwide]

Re: Yamaha F15 key switch?

I plan to go through all the connections again once I get it on the trailer and all is easier to access. For whatever reason, when all the connections line up, it fires off real strong, but then it just doesn't seem to get enough juice through on other occasions. I'm not real familiar with how the solenoid is put together inside as to how the conacts would be good most of the time and then off another.

Thanks - Open Wide

 

[99yam40]

Re: Yamaha F15 key switch?

All electrical connections including the contacts in relay can get high resistance due to oxidation/ burning and cause low voltage to starter motor and then arc through the oxide( high resistance) to complete a good connection for a little while.
Volt meter will help find it