20 hp 4 strokes accelerator pump

[Sylva-Ranger]

I want to check accelerator pump operation on a 2012 mercury 20 hp 4 strokes S/N 0R 509781

Put the serial number in this link and go to "carburetor " (sorry can't put the picture directly)

https://www.mercurymarine.com/en/ca/.../parts-catalog

If i remove the fuel bowl (20) , pump some fuel in the bowl and activate the accelerator pump plunger (30) by hand , that prime some fuel in a small hole directly in the bottom of the fuel bowl.

if i remember, usualy, instead of going out by this small hole when activate the plunger, the fuel is supposed to go out by the check valve ( 25) ?

And after that, the fuel that going out by this check valve is supposed to going into the ventury by a small passage ?

At this time, when the plunger is activate, the fuel simply return in the fuel bowl , not very usefull

if i'm wright , what can be going wrong ?



Also, on the part catalog above, they put an o-ring (42) near the plunger or near is spring …….I can't figure out where is this 0-ring …

I have the 2 o-rings (37) in the carburetor, but not the o-ring (42) .

Thank you !