Motor won't start at the lake, but it will at home.

[usmc7051]

I have a 2010 Yamaha 40hp four stroke. I have never ran into this issue before. Two weeks ago we were out fishing and when it was time to head in the motor would not start. I had to use my *****ing motor to get back to the dock. The next weekend, I checked out the engine, changed spark plugs, changed the oil, checked the fuel system, and everything checked out. Hooked up a garden hose to the water intake and the motor started right up and idled perfect. I ran it for about ten minutes and shut it down. Waited about an hour and then it started right up again. Disconnected everything and went to the lake, launched, and when I tried to start it, it would not start. After about half hour trying to start it, I reloaded onto the trailer and took it out of the water. When I got home I hooked up the water hose and it started right up with no problems, Idled great, and no sputtering when running up the throttle. This weekend I tried again with the same results. It will start at home, both with the garden hose and with the motor sitting in a tub of water. But when I launch at the lake it will not start.

Any Ideas?
Thanks,
Brian

[bajakeith]

lake no start

the motor will be at a richer mixture in the lake, due to water restriction...and is this lake at a high alttitude ? those (4) carbs on that motor are very picky varmits !!! I have had to clean them twice on more than one job to get them to run right!!!!! LOL.....K

[usmc7051]

Lake altitude

The altitude at home is 2558. and the lake is at 2605. About ten miles from home to the lake.

[99yam40]

need to see if it is getting spark when it will not start so you know what to chase spark or fuel

[usmc7051]

spark or not?

I will check the spark next time up there. The thing that really makes me mad is that the warranty ran out 3 weeks ago.

[BQUICK]

Also, with motor in the water there is back pressure on the exhaust. That coupled with the altitude could make it more difficult to get started.