Further to this. If it has the original lift pump fitted they have a NRV in them. Cheaper after market ones don't have NRVs, so if they fail the injection pump can easily suck fuel from tank but power will be low on hills. Specially with low fuel levels. If the lift pump has failed the NRVs are so strong they can prevent the injection pump sucking fuel from the tank. I had this happen to mine and it had a new injection pump fitted. So it may not be the injection pump that has failed. Look in the tech archive, i posted a guide in there how to test lift pump for flow. No need to remove any pipes though. Just look for air in the clear pipe from filter to injection pump. If you have air in there it will be lift pump failed. If there is air remove relay 12 and with ignition off power terminal five socket, the one nearest front of car from battery positive. You should see the air move if it doesn't lift pump is duff.