Hi, I got this motor in on trade in and it needed work. Hooking up a new fuel tank and line to fuel filter, then replacing punky line between fuel filter and pump. Got out broken off low speed needle in one of the carbs and replaced it. Set at about 3 1/2 turns and motor runs great. Also cleaned out fuel pump and made sure the reed valves were centered over ports........they will not line up properly if you expect the pegs to ensure the alignment. Diaphram looked good.
Problem is that under full speed only and after at least a 4 minute run......the motor will run lean and slow down until you pump the sqweeze bulb. Then will recover and run ok for another minute or two. I tried 3 different tanks and also rechecked the fuel filter and pump. No leaks or flattened hoses while running or at rest. My guess is that the fuel pumps are typically engineered close to the edge and maybe cant suck hard enough to gain fuel supply from a fuel tank with a 12' hose. I have added hose length to most of my motors but maybe this won't work on this particular application. Some of my OMC's pull through a 20' 3/8 or 5/16 hose.
What is going on? Maybe just a weak pump? Customer is frustrated and soon will ask for a refund if I can't get this problem resolved. The motor is very low hours and almost like new. I sold it to him for $1,600. yamaha 25 2004 2cycle 001.jpgyamaha 25 2004 2cycle 003.jpgyamaha 25 2004 2cycle 005.jpgThanks.....Tim