A quick update on this one in case anyone else comes across a similar problem.
Couldn't trace the fault myself so called the AA.
There was not enough power getting to the
or the injectors - only around 2 volts.
With the main relay removed & a jumper wire connected across the terminals it started.
The problem was the earth wire which runs from the main relay to the
. Seems its not earthing.
That earth has now been cut & a new earth connection created running from relay earth to battery negative terminal.
Only problem now is the relays are staying powered up and draining power from the battery. Have installed an inline switch to break the circuit when engine switched off.
All a bit strange how these things can just happen out of the blue!