when the car is left stood, the fuel backs up into the tank. it doesnt happen every time, but when on a hill, it will do this more often than not. i have changed the filter, filter housing, bled from the pump and checked the push fit fuel pipes

can anyone help?? any suggestions would be appreciated

 

change pipe from filter to pump for a clear one with pipe clips first. then check the pipes right under the drivers seat [some had joints there as well] the clear pipe is so u can see whats going on, my money is on one of the pushfits being dodgy maybe even the one on the tank