Thanks guys, yes this one does have the immobiliser ring around ign barrel - I've had it off & cleaned connections, still no go - any suggestions of how to by-pass this ?? - - 4 wires going into it - red is live / also key doesn't have buttons so what activates what ??

Have replaced fuel pump, filter, injectors, got good fuel pressure at union before injectors. Have replaced crank movement sensor, cam sensor & now computer - but still only gives one fire. It does keep running on aero-start - so something's locking the fuel off. Any thoughts ??