Factory VY LPG electrical operation

[Nathern]

I have a problem that has shown up on 2 different VY series 2 with factory Lpg systems and was wondering if any body understands how the electrical control for the Lpg works
The engine will randomly stop when on Lpg .
Today for example I had been driving for approximately 10 minutes on the highway when the engine dies, no warning, just stops. alternator light is on but no other faults. Coast to the side of the road, engine cranks but no start. tried twice and check alternator came on, (think this is a red herring). Switched to petrol and engine started straight away, all warning lights off and dash says system OK. Turned engine off and switched back to Lpg and cranks but no start. Restart on petrol and drive away, within a minute I switch back to Lpg and it runs perfectly.

I think the lpg valves are closing and shutting of lpg supply to the regulator. What sensor tells the lpg sensor to turn on as it only turns on briefly when the ignition is first turned on and then when the engine is running

 

[cor3yz]

Depending on the system they have a safety switch. Which is basically a relay that is switched by a neg coil pulse.
It will turn on for a few seconds on ignition and be on solid when the car is running.
Sometimes these are separate and other times they are built into the lpg processor ECU.

 

[Nathern]

Thanks that was as I suspected, I traced the regulator control valve back to a control module mounted on the safety control valve on the tank.
The control module has an earth, 12v supply, and a wire from the Pcm. The wire from the Pcm supplies a 12v pulse which is interdependent of RPM.
does any body no if these control units have a history of failure, I don't think it is the Pcm as you can switch it straight to petrol and it will run straight away.
All connectors look good and wiring looks undamaged

 

[Nathern]

SO pulled the " smart relay off tank and immediately say from it construction where the problem could be. and on further investigation fount the contacts for the coil cracked where they were soldered to the PCB . Very bad design right from the start. I have included photos to illustrate.
Luckily easily fixed.
1 Gently remove black plastic cover using sharp knife to pull plastic away from resin.
2 gently break off the brittle resin on the top of PCB near the terminals of the coil until solder terminals exposed
3 re-solder
4 tape board to coil to stop flex and solder joints from breaking

 

[cor3yz]

Glad to hear its all sorted. I'm not a fan of the smart solenoid locks. It also appears that the impco control box sends LPG power to the tank and then through the smart valve and back to the under bonnet lock off.
Seems silly when the control box is simply on the other side of the firewall

 

[Proto]

Hey I just recently brought a 2003 VY Commodore that has LPG but I’ve been trying to find where the switch could be because the car Carley doesn’t have a switch to turn the LPG off to go to petrol and I was wondering if anyone knew how I could turn the petrol on instead of running LPG

 

[J_D 2.0]

Hey I just recently brought a 2003 VY Commodore that has LPG but I’ve been trying to find where the switch could be because the car Carley doesn’t have a switch to turn the LPG off to go to petrol and I was wondering if anyone knew how I could turn the petrol on instead of running LPG

If it’s dual fuel it has to have a switch somewhere to change from LPG to petrol. Are you sure it hasn’t been converted to straight LPG?

 

[Proto]

I have no idea it says it has a fuel gauge problem on the Speedo