2003 Ecotec engine (Astra 2.0 DT Sri) - locate cut off solenoid?

My Astra died some time ago. Has done 68000 miles. Turns over, won't fire.When ignition turned on no Engine Management light etc. Looks normal. Have tried spill back pipe test but still no go.
Neighbour who was mechanic for 30+ years reckons it may be cut off solenoid. He's recently been ill with cancer and can't do anything but has advised what to do - but although he described the solenoid we can't find where it actually is. Can anyone advise please (a pic would be good ....)
Cheers
Jay