Losing Fuel Prime on Yamaha ??

[tperk100]

Previous to owning this 1997 2 stroke Yamaha 150, I owned 4 other 2 strokes. My experience has always been that it was necessary to hand pump the primer bulb until it became so hard/stiff that you could not really pump it up any more.

On this engine the bulb never gets "hard." I pump it up until I feel only a very small amount of resistance and the engine starts fine. HOWEVER, after being on the water fishing for a couple of hours without running the engine, and then trying to re-start, sometimes I have to pump the bulb up again.

Maybe I am losing prime? Or is it something else? How do I troubleshoot this? Why does the bulb not became "hard" when I pump it?

Don't know if this has anything to do with it, but I keep the boat in my garage, and there is usually at least a little odor of gasoline present.

Thanks for any help.

 

[rodbolt]

Re: Losing Fuel Prime on Yamaha ??

I would carefully inspect or replace the two lift pumps.

 

[nelbur]

Re: Losing Fuel Prime on Yamaha ??

Whether the bulb gets hard or not has more to do with the bulb and it's valves than anything motor related. Some bulbs have plastic flapper type valves that seal poorly and some fuel runs by the closed valve when you are squeezing it. The loss of prime could be due to a malfunctioning antisiphon valve at your fuel tank. It should not allow fuel to run back into the tank from the engine.