Yamaha F100 check valve

Petra

Recruit
Joined
Aug 19, 2022
Messages
1
I have been working on a Yamaha F100AET.
Whilst replacing the intake manifold gasket and O-Rings I became suspicious of the check valve 67F-14860-00-00.
When the diaphragm is operated air can be heard in the area of the check valve but I can not detect any air flow at the pipes that connect to the Carburettors. I suspect that the check valve will need replacing, however I have noticed that earlier versions of this power head used a more basic check valve 67F-13183-00-00 (item #2, hose #3 goes to the diaphragm) and a number of "T" pieces but what I don't understand is how does the system work with only one check valve.
Hoping some kind sole can explain
regards, Petra

check valve  67F-13183-00-00.PNG
 
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