1990 Yamaha 115 Stalls in Idle

[Daewoo2]

Hi guys I got this problem because I was lazy and I knew better. So now I have to deal with it and correct the problem. The problem is that I let the boat sit for about 6 months with out running it. So there is no question that the gas in the tank is old and probably foul and has water in it from condensation. The motor starts up fine but won't stay in idle for more than 10 secs. If I push the choke just before it begins to die the rpms come back until I have to repeat the process. Well by pushing in the choke and giving the motor throttle I got the boat on plane and it will run without stalling and without the choke from 2000 rpms to wot. It does surge and bog down but won't stall. As soon as I back down to idle it will stall in 10secs again.<br /><br />The questions are <br />1. Can I run all the old gas out of the tank then restart with fresh gas<br />2. Will replacing the fuel water separtor help. It probably needs to be replaced maybe not.<br /><br />What I am getting at Is there anyway of getting around draining the fuel tank. There would be probably 25 gallons to drain. Any of your advice would be helpful whatever it may be.<br />Thanks for you time

 

[rodbolt]

Re: 1990 Yamaha 115 Stalls in Idle

hello<br /> wow<br /> you must like buying pistons <br /> I am sure the local dealer will like it <br /> anyway the reason it wont idle and surges is because its running out of fuel. LEAN. LEAN is BAD.<br /> remove and clean the carbs and the pump. clean and flush the lines. pump the tank and dispose of the fuel. a tank of gas costs less than a powerhead gasket set.anything that goes in the carbs has to assist in lubricating the moving parts. old gas tends to form a black shiney laquer looking varnish that adheres to piston skirts and causes pistons to stick and scuff.<br /> good luck and dont run the motor anymore until its fixed

 

[arboatdr]

Re: 1990 Yamaha 115 Stalls in Idle

what rodbolt said!!

 

[elcamino12sec]

Re: 1990 Yamaha 115 Stalls in Idle

I have came across this myself and this is what I did. I got about 5 more feet of fuel line and used my primer bulb as a siphon (however you spell it) and put it im my 5 gallon tank I for my lawn and garden equipment. After about 2 weeks and five gallons at a time I had an empty tank. I distributed it to my cars and other equipment little by little. Its just a sudggestion though.<br />Oh, and change the water seperator/fuel filter before and after you get rid of the bad gas.

 

[Daewoo2]

Re: 1990 Yamaha 115 Stalls in Idle

Ok I understand draining the fuel tank and flushing the lines. Then cleaning the carbs. What I don't understand is why would it be running lean. It is getting oil because it smokes when you start it up. I don't premix because it uses oil injection. Is it a different term then what I am thinking of

 

[jim dozier]

Re: 1990 Yamaha 115 Stalls in Idle

It is running lean because while it sat the gas in the carbs polymerized (turned to varnish) and your formerly correct orifices are now smaller than they should be and are supplying less gas each time the engine sucks air past it. The idle circuits are more susceptible to this than the main jets but the same could be happening to the mains. You might get by by enrichening the idle circuit but more likely it is time to do a thorough carb cleaning/rebuild.