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Air coming from clear tube from the fuel pump to carb???

S

Sara Noel Hurtado

New member
I have a 1987 Mercruiser 3.0
The clear tube from the fuel pump to the carb thats meant if the diaphragm ruptures, its either sucking in air or pushing out here. When we hook it up to the carb you can hear it going puff, puff, puff..no fuel in the clear hose, just air? Any help?!?
 
To have the diaphragm operate properly it needs a vent. On auto applications they just drill a hole and the gas goes to the ground. On a boat that is unacceptable so they install a fitting. Without the hose connected you have basically a car pump. Again dumping the fuel into the bilge is not a good idea. So a hose directs any fuel to the carb body. The pulsating you feel is the diaphragm going upward, (suction) and going downward (pressure)
perfectly normal.
 
If it is the intake valve thats making that noise, would you hear it through that hose? When we have the clear hose connected to both fuel pump and carb and pinch the hose it stops making the noise.
 
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