Simon is right. A pound to a penny it is the fuel pump relay , check that first before spending any money on pumps.
Easy to check , does the fuel pump "whine" when you switch on , if it doesn't it is almost certainly the relay.
If the fuel pump does "whine" on ignition then it is possibly the pump, but there are other causes. Not sure if the set up on this engine has a pressure relief valve, but if it does then this can be a source of problems.
