No, mates, fuel
is actually transferred from the center to the main tank.
The forward pump creates an additional flow to the tank itself, and as Bernoulli demonstrated, this creates a low pressure which "pulls" the center tank fuel into the main one.
Even if the main tank is full initially, it is this circulation of fuel which creates the suction to the main tank anyways. In this particular case, the center tank fuel will "be ready" to replace the main tank fuel used by the engine until the operation stops.
More complicated to explain than actually is.
I'm talking about classic, don't know if NG is different, but a scavenge jet pump is a scavenge jet pump.
