Technical Fuel pump

[Davefridge]

The pump takes fuel from the tank, the fuel level drops and forms a vacuum in the tank there is a
breather often in the fuel cap that lets air into the tank if this is blocked vacuum will build up in
the tank and stop the fuel flow. If you give it a test with the tank cap loose and it still has the fault
then it's not this. if the car runs ok then it's likely you have a blocked breather.

As far as I know there isn't a vent in the cap. We're not allowed to vent fumes into the atmosphere like we used to!

 

[RalphM]

There has to be a vent of some kind or the pump could not pump fuel from the tank my 2006 panda as one in the cap.