2003 S80 bi-fuel won’t switch to LPG

[Bu5hy]

recently bought a 2003 s80 bi-fuel ( wife won’t let me drive the 2.5T anymore) anyway got it for a steel as the LPG system didn’t work , as I said to the wife “how hard can I be ?” Well :
1. Changed the vapourisor elbow and solenoid
2. fitted a new filter
3. Checked fuses
4. Stripped down the distributor , cleaned thoroughly and found a small piece of (possibly O ring ) stuck in the side of the stepper motor , gave it a little push and it popped out , I now know this was not a good think to do .
5. Found a faulty injector and replaced for new .
6. Checked the plugs ( they’re the multi point type ) going to change for bog standard NGK
7. Got plenty of heat circulating around the regulator.
8. Got a click sound from the boot area when operating the switch but not from the solenoid under the bonnet .
9. Tank is 3/4 full and as metioned there’s gas to the dizzy
10 . Screemed “why won’t you work” at it !

I’ve read all the posts a learnt plenty from the guys on here , I’d be happy right now if it just ran a little , even if it was rough , cut out after 10 miles , misfired , backfired or just broke wind !

Autogas 2000 have been great so far and I’d recommend them highly.

Is there anyone out there with any help , advise or similar experience to mine please ?