Yamaha fuel bulb instantly colapses.

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cyclops2

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friends old & 2 new fuel bulbs collapse in seconds. No leaks according to him or our noses. If I squeez any bulbs. I can feel & hear the fuel squirting back into the fuel tank. Even tried putting the bulb in backwards. STILL NO firm bulb.
Bad batch of new fuel bulbs ?
I never had a Yamaha. Are they so different than a Evinrude O B setup ?
 
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99yam40

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Re: Yamaha fuel bulb instantly colapses.

If the bulb collapses with motor running then there is a restriction somewhere back to tank

The bulb should not pump fuel to the tank, but you can hear it pump fuel to motor and it should become firm if pumps and other float systems close off after full properly
 
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cyclops2

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Re: Yamaha fuel bulb instantly colapses.

All the bulbs collapse just by squeezing them while rapidly trying to fill the bulb. The engine will idle for a minute OK, then the idle slows down to a stall out. pump the bulb till some build up must be refilling the carb. I looked around the motor & on the water for raw gasoline. None.

Is there some kind of check valve in Yamaha tank to only allow fuel out ? Correction..........He is using a red plastic fuel tank.

The engine runs ok at 1/4 or more of RPMs. Still has the softish bulb.

Could the bulbs have check valves in wrong places or direction ? Hate seeeing the 70 ish guy gouing out with such a unsafe setup.
 
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99yam40

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Re: Yamaha fuel bulb instantly colapses.

Bulb should pump fuel until lines, fuel pump, and carbs are full and then become firm (hard)as no more fuel has anywhere to go.
If it will not do this then something is leaking fuel or you are sucking air.
As I said before bulb will not stay firm while fuel pump is sucking on it

Have you made sure the arrow on bulb is pointed toward the motor?
and while pumping primer hold bulb so that the arrow is pointed up (vertical) so that the bulb fills with fuel and the check valves in both ends of the bulb can work properly.

Maybe the fuel pump diaphragm has a hole in it
 
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renegade15

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Re: Yamaha fuel bulb instantly colapses.

You said red plastic tank, is it a portable tank? Is the vent open fully on the tank? On some tanks you can remove the supply tube and inspect it. Is there an inline fuel filter before the bulb that may be restricting flow? Can you try another tank? I'd be willing to bet any decent shop would let you borrow a portable tank to test for tank restriction. Are there hose clamps on all hose fittings?
 
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cyclops2

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Re: Yamaha fuel bulb instantly colapses.

Tried all of those.
My Evinrude does stay fully hard while running. Fuel out means equal amount must be pulled in, IF the bulb is stiff enough rubber to hold shape. I will check his setup out by using my bulb & hose with his fittings.
Thanks 99yam.
 
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