fuel leak or auxiliary fuel pump malfunction?

From time to time pilots have observed fuel stains on the nosewheel
wheelpant of our club's 172SP. The only time I have actually seen fuel
dripping from the engine was when I watched a pilot turn the auxiliary
fuel pump on for what seemed to me to be an excessively long period of
time. The fuel appeared to be dripping out of one of the two plastic
hoses that come down through the cowling just ahead of the firewall. I
have assumed that the cure is to prime the engine according to the POH:


5. Auxiliary Fuel Pump Switch -- ON.

6. Misture -- ADVANCE until fuel flow just starts to rise, then return
to IDLE CUT OFF position.

7. Auxiliary Fuel Pump -- OFF.

When I follow this procedure, I never see fuel stains on the nosewheel
wheelpant.

One of our pilots has suggested that fuel should not drain from the
engine when the auxiliary fuel pump is left on too long. He thinks
there is a leak in the fuel system.

Does anyone know the answer to this question?

Thanks

Stephen Ashley