Fuel pump clear vent tube

[Mskeels]

No real importance just trying to learn. I have twin engines. One fuel pump the clear fuel vent pipe to the carb has a suck and blow sensation on the end of the pipe when removed from the carb. The other has nothing when removed. The one that has nothing has running issues in general.
Surely the suck and blow is the diaphragm moving in the pump?

 

[alldodge]

The clear Tygon tubing is connected between the primary and secondary diaphragm. If primary ruptures then fuel should be pushed up the tube and in the carb.

The one which your getting nothing may have a issue with secondary diaphragm. Check fuel pressure, should be 3-7 psi.

 

[Bondo]

No real importance just trying to learn. I have twin engines. One fuel pump the clear fuel vent pipe to the carb has a suck and blow sensation on the end of the pipe when removed from the carb. The other has nothing when removed. The one that has nothing has running issues in general.
Surely the suck and blow is the diaphragm moving in the pump?

Ayuh,..... Welcome Aboard,..... Yer right,.... I'd be lookin' at the other fuel pump,.....

 

[Scott Danforth]

I would be buying two new mechanical pumps