Where would they hide the fuel switch over solenoid on a BA Falcon?

[It'sNotWorthComplaining!]

My wife's BA falcon has an Impco vapor system, it should start on petrol and then switch over to LPG after start.
Cold starts are a problem, it seems to cut off the petrol too fast so the gas stalls the car.
I took it to an LPG place left it there a day and they told me they incremented the settings bit by bit on the controller. Any was took it home and still have this problem.
It will start if we switch it onto petrol and once running switch it to gas it runs.
I had a look under the drivers fuse compartment expecting to see the switch module , but cant find one.
Where would a fitter install it???
I would like to replace this part as I reckon it is faulty as it doesn't allow petrol injection for a long enough period.

[bee utey]

The BA has the ECU under the bonnet so the injector cut relay should be connected to the loom between the engine and the ECU? I can't remember, it's ages since I put a vapour system on a BA. Anyway, there's no problem starting on petrol and switching to gas after a couple of seconds, you just have to remember!

[It'sNotWorthComplaining!]

The problem I have if it was there originally , then I Iike to restore things the way they should work.
I took it to a LPG Specialist??? he had it for a day and did ïncriment adjustments "he said, and it started properly each time. He is out of business now . I just see where he made these adjustments as I can't find any part to adjust.
a series of pics follow on the installation.

setup
https://www.aulro.com/afvb/images/imported/2012/05/1550.jpg

Wires for ???

https://www.aulro.com/afvb/images/imported/2012/05/1551.jpg

https://www.aulro.com/afvb/images/imported/2012/05/1552.jpg

These wires appear to come out of an lpg loom that is attached to a shielded LPG supply line from the rear tank
https://www.aulro.com/afvb/images/imported/2012/05/1553.jpg
The black wire to the bolt is labled LPG loom on sticker The Engine ECU is is just right of the edge of this pic , ( not seen) but there is no LPG control module of any sort near it. so its got me baffled how the timing switch over takes place automatically and how this LPG expert actually reckons he made adjustments.
https://www.aulro.com/afvb/images/imported/2012/05/1554.jpg

[bee utey]

Well if you haven't found the control box, you haven't looked far enough. The wires to the tank go to the tank shut-off valve and the gauge sender. Unlikely a petrol shut-off relay to be found there. The purple and yellow wires go to the mixture control valve. Aha! Try tracing back these wires in the lpg loom, they will originate from the control box. I see a grommet next the brake booster, per chance is there stuff connected on the inside of the firewall? What is on the end of the loom going around the brake booster?

[It'sNotWorthComplaining!]

Yes I expected it to be from that wire entry through the fire wall next to b/Booster to be able to see something, looks like a dash pull apart a bit further..
Thanks mate for taking interest and time replying
cheers:)