2005 Yamaha 250 4-stroke stalling at low speed

[fishlips]

282 sailfish with twin 250's. Starboard engine began sputtering and then stalled after about 1-1/2 hrs of low speed trolling (6-8k rpm). Found ball priming pump not full and took longer time than normal to get it full. Restarted engine fine. Ran at crusing speed for about 20 min and engine ran fine. When went back to trolling speed same sputtering /stall occurred again after about an hour or so. Pumped primer ball again, restarted and ran fine again until same sequence repeated one more time. Ran at cruising speed for about 30 minutes on the way back to dock with no problems. Just had full spring maintenance performed on both engines and fuel tank was topped off with fresh, ethanal treated gasoline. Any suggestions / troubleshooting recommendations?

 

[Halfhitch]

My first suspicion would be that spring maintenance that was performed. Check everything they did for proper installation. Fuel/water filter/separator tight? Check to make sure the old gasket didn't get stuck to the housing when they removed the old filter and wound up with two gaskets on the new filter. A not too uncommon thing. Check the little on-engine fuel filter cup with the red indicator ring. Make sure that is sealed well. Check for any kinked fuel lines that may have been pushed out of the way for said service. Thats a place to start. Next time you go out and the engine starts to stumble, immediately pump the primer bulb. If that brings the engine back to proper performance, then suspicion the low pressure fuel pump. It's an easy do-it-yourself job. My F225 is one year older than yours and I just changed it so your year model is in that age group. First though check the recent work. Fuel pump problems generally show up under heavy acceleration, not idling. Good luck. let us know what you find.

 

[kirk a]

You might also try adding a higher dose of fuel attitive, ring free, or other. It does not take much to clog up a filter, particularly those in the VST.