I have a 2.5 diesel boxer non HDi, when I try to start the engine, it starts and cuts out, it has a new fuel filter, I have bleeded the fuel through to the injectors, I have taken out the sender unit from the tank the filter is clean no dirt showing, could this be the cut off solenoid playing up if so can any tell how to remove it. the engine is a DJ5 engine with a Bosch injector pump, also do’s any know what the switch is on top of the pump its like a micro switch.