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Primer bulb

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dcso408

Member
"why would my primer bulb lose

"why would my primer bulb lose pressure if i turn it so the arrow is pointed down, if i turn it so it faces up it holds pressure
ted"
 
"Thats normal due to the check

"Thats normal due to the check valves in it . It is only under pressure when you pump it up to get fuel in the carbs. Once the motor is started it is no longer under pressure, there is a suction in the bulb and fuel line to suck fuel from the tank."
 
"then it shouldn't let fue

"then it shouldn't let fuel flow back, correct? when i pump it and holding it so the arrow is pointed up it doesnt build pressure, turn it the other way (arrow up) and it builds pressure
ted"
 
"The valves in the fuel primer

"The valves in the fuel primer bulb are not spring loaded valves, they simply function due to gravity, and air/fuel pressure when pumped.

Why would you want to hold it upside down anyway?"
 
"i dont, i was just under the

"i dont, i was just under the assumption that there might be an anti siphon type valve in there. the only way it seems to work ( build that intial line pressure)is if you hold it vertically with the arrow down. i was under the assumption it should work no matter what way you held it.
ted"
 
"That's why a anti siphon

"That's why a anti siphon valve is an essential part of the build in fuel tanks, located right where the fuel hose attaches to the tank fitting. It prevents fuel from draining from the tank should the hose be leaking and lower than the tank at some point, and it also prevents fuel from draining from the engine back into the tank."
 
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