properly and they are in good working order, they do not leak . To check this, you must supply the same pressure to both the diaphragm and the recirc inlet - if you do this, the pressure applied at the valve cannot and will not cause the recirc to open.
The diaphragm has considerably more surface area than the valve, so with the pressure being equal on both sides there will always be a greater force holding the valve closed under WOT conditions.