Motor question?

[brian m]

Hey guys I have a 89 yamaha prov that is losing power when on plane. Where should I start? The ball does have a few small tiny cracks by the hose clamps but how do I know if thats the cause? I know I should replace it but is there a well of telling ........maybe gas leaking or air getting in. Where should I start ?Thanks Brian

[Gator]

I have a 94 Pro-V.

If you have cracks in the bulb, start there. That's probably the likely culprit, changing the air/fuel mixture needed to run the motor. Easy to change and not too expensive.

[brian m]

Ill start with the ball tomorrow and see what that does

[FRANK D. LOZANO]

Hey Brian,

I posted this some time ago but it is worth repeating. This is one of the best methods of diagnosing a fuel problem on a carburetted motor.

Gator is right, change the ball and fuel line first.


Good luck, give me a ring if you get stuck.



Frank Lozano


· Pump the fuel ball while it is acting up. If the power comes back then you most likely have a bad fuel pump or a fuel filter plugging up. By pumping the ball you bypass the fuel pumps.

· If the ball is flat and won’t pump up it is a restriction is the fuel line or tank system.

· If the ball is soft and won’t pump up you may just have a bad ball, the fuel ball and its check valve are an integral component of the fuel pumps and fuel system. The check valve holds fuel while the pump draws it.

· If it is not the ball or the fuel pumps it sounds like the carbs may be varnished up and may need to be overhauled. If the unit has been sitting it may be the cause. If it is the carbs or the problem still exists do not continue to run it with out getting the problem corrected.

When is the last time you had the unit tuned? If it’s been over 2 years get it done regardless of hours. Time vs. hours

[brian m]

Frank sent you a PM