View Full Version : Yamaha 50 litre fuel supply problem

09-05-2007, 09:59 AM
"Every once in a while, when I start my 5.0 litre yamaha, it will run for a minute and then stall. There is no fuel in the carb and pumping the throttle does not prime the carb. If I pour gas into the carb, it runs for 10 seconds and dies again. It typically will not start the rest of that day and will start and work fine the next day. I know it is not getting fuel but cannot figure out why the fuel does not flow for one day and then will work fine the next. I don't think it is vapor locked as the engine is cold when this happens. It has never happened when the engine is warm and otherwise, the engine runs great. Any suggestions as to what to troubleshoot would be appreciated."

09-06-2007, 12:24 AM
"you need to talk to Capt ken. I have the 4.3 Yamaha stern drive that is very hard to start for the first time, once it starts it will start the rest of the day. Sounds like I am not getting fuel to the carb first thing. from what I understand is this. When I turn the key fuel is suppose to go to the carb, mine is not. So It takes londer for the Carb to get the gas. Once there it is fine the rest of the day.

Capt ken will know for sure."

09-08-2007, 10:41 PM
"You may have a leaking check valve in the pump allowing fuel to leak back to the tank. Install a outboard primer bulb ahead of the fuel filter, then pump it up before starting the engine. If the engine starts easy then check for air leaks in the fuel system. If non is found, you can replace the fuel pump. Or just leave the primer bulb in the system and prime it up before starting."