At 10:31 PM 2/13/2013, neil n wrote:
>say, closed more than 50%, as long as the fuel tank is properly
>vented, it should make no difference to the pump.  (he says with a

Fuel tank venting isn't particularly relevant here, I think.  You're
pulling 60 liters per hour out of the tank and putting it right back
in, minus the amount the engine actually consumes.  If the tank
venting can't keep up with consumption the tank will collapse from
external pressure, at which point a noisy fuel pump will be a
secondary consideration.

Yrs,
d