1995 Yamaha 2 cycle C85 will not start after sitting 5 weeks

[fatlaz]

I live in St. Louis, so we have both cold and hot weather this time of year. I have a pontoon that stays in the water year round. Usually I will run the fuel out of the motor before letting it sit this long, but the weather got bad, then we had a hot spell. Went to start it. It will start with choke, run fast, then dies. Sprayed carb cleaner in it will run off the carb cleaner, but dies. Thought maybe fuel filter was blocked, removed hose between fuel pump and carb, then pumped ball, fuel ran freely. So I'm getting spark and air. Could it just be dirty carbs? Will carb spray clean the carb to get it running.? Could fuel pump be bad? Do i need to fix it before spring, or should I just wait until spring?

 

[rejesterd]

Yeah, I would assume it's stale fuel. I would at least drain the carburetors before storing it for the winter.

Get an auxiliary fuel tank, fill it with fresh fuel and run the engine off that. If performance improves, then you know you need to clean out your tank and fuel hoses going into the engine. If it still struggles to run, then take the carburetors apart and clean them.

If it still struggles to run after that, check the fuel pump diaphragm for leaks. If you find a leak, replace the diaphragm. Also, you probably want to drain the engine oil, as fuel may have gotten in there. If you don't find a leak, try pumping the bulb after starting the engine to see if it stays running. If it does stay running, then just replace the entire pump.

 

[99yam40]

spraying carb cleaner into the carb throats does nothing but harm the motor because it has no lubrication in it, do not ever do that.
carbs need to be taken apart and cleaned properly and the follow the link and sync procedures in service manual after putting the cleaned carbs back on.

Oh yea, a C85 has no engine oil so take some of the info you get here with the understanding it is worth what you paid for the info

 

[Silvertip]

You are running the engine dry when the boat sits for an extended period. That is not necessary and with air instead of fuel in the carbs, the oil from the fuel mixture can get gummy and create the problem you are having. Use a fuel stabilizer (Stabil, SeaFoam, or any of the gazillion others) in your fuel. But very likely carb cleaning is fix.