Hi thanks for the replies, Bryan have tried removing plunger and spring. still cuts out, also ignition switch will still stop engine.
James not tried water, interesting idea.
John the C.A.S appears to be for rev counter only,car will start and run ok without it.
Working on it today, just as it cut out my phone rang so i jumped out to answer it forgetting to switch the ignition off. Went back to it about half an hour later, would not start, switched ignition off for half an hour, starts and runs, so i'm thinking electric. Trying to find wiring diagram, there are wires going into the back of the pump so not ruled that out yet.
Thanks
Tommy