>>>>with a safety valve that requires 1.5 bar to open before it will start, my low pressure pump develops app 6.0 bar before the filter, and 2.2 bar after the filter, filter has been replaced, filter has 5 pipe connections at top of filter. John<<<< This must be loosing pressure at the filter, has it any pressure relief valves in any of the 5 pipes? I don't know if it should have but if the pressure is dropping to 1.5 bar and cutting the engine then it looks like the fault is here somewhere.