Just completing my Haynes roadster build with 1.8 L Sierra CVH engine, now doing the wiring. I have wired up the starter, alternator and ignition circuits according to Sierra wiring diagram. Engine turns over but no ignition. Checked and no spark at spark plugs. Checked and rechecked wiring and everything is connected OK. I have not wired up the instrument panel (these wires are cut on approach to panel and awaiting connection later) and I have removed the anti theft system wiring (this includes the black lead from the ignition coil primary circuit; so ignition coil only has green feed wire and HT cable, no second wire on +/15 terminal).

I have checked continuity of wires with a multimeter, cleaned contacts and tested resistance in primary and secondary circuits of ignition coil; all OK.

The original ECU is fitted into the circuit with the three sensors feeding into it (engine temp, air temp and crank position sensor), also valve system and relay to automatic choke are all in place. Relay tested and works. The only thing I can't check is the ECU however the original Sierra was working fine before dismantling, engine has been completely cleaned and rebuilt and turns over fine. There is no reason why any parts should suddenly be faulty.

I have checked that voltage is flowing to ECU on turing ignition and all is OK. However, I can't demonstrate a voltage from ECU to ignition coil (on green wire) and I am unsure if this is because there is a problem or that it is because this current is intermittent to energise and then repeatedly collapse the primary coil magnetic field.

Grateful for advice on things that I could also check and potential solutions. If there is an auto electrician close to Truro in Cornwall that would be ideal. All expert help gratefully received. I expect everyone is at Donnignton this weekend (wish I was), so I will wait patiently for response.
Thanks

Fixed it!!!!

The black lead that went from the ignition coil to the vehicle antitheft module I had cut, thinking it was not needed as I will not be reusing the antitheft electrics. I now realise it is the power feed to the ignition coil. I was always confused why this lead was connected to the +/15 terminal on the primary circuit (Doh!)

The green wire connecting coil to ECU, which I thought was the power feed, is in fact the control switch from the ECU so I had no voltage going to coil.

I have now connected the black wire to a 12v feed and car started first time!!!! Yahey!

My depression is lifted and the build can continue.

If anyone has the same problem then this solo question and answer session may help...