vx v6 with fact lpg starting gremlins

[commsirac]

Hi there.
As the title suggests, have an issue when starting the car on lpg.....it wont start and causes a backfire in the inlet manifold when releasing the key. This only happens on the odd occasion after the car has been sitting for 15mins to ~2hours after achieving running temperature. it appears that the problem may be electrical, something stopping power going to the ignition when first attempting to crank it and returning the power when releasing the key to cause the backfire........but willing to listen to other suggestions. Have heard about key problems, on the first non start, have removed the key and tried again and it starts instantly. As yet the problem hasnt replicated itself on petrol. The car has been recently serviced by a workshop specialising in lpg tuning and they cant fault it.
Any suggestions?
Thankyou

[Bent_6]

I'm having a similar problem with mine, i have a S1 VT which has a factory gas memcal running the system.
When the weather is really cold it is a prick to start, pops and splutters and wont run unless i run the key on for a few seconds after the initial fire.
I took it to the guy who installed it originally and he told me the factory system starts on petrol and automatically changes after a second to gas.
He reckons the problem im having is that the mix needs adjusting as its not right at start up.
I'ts going in on Monday arvo, if it is any better i'll let u know.

[commsirac]

Dont think the vx fact system is the same, according to my repairer it doesnt start on petrol entirely but uses a tiny amount of petrol along with the gas, which it also does on full throttle...apparently. Mine starts perfectly if the motor is cold and runs perfectly once started.

[muney]

i reckon you guys need a tune..my vt starts no problem first go..rain, hail or shine..go back to the installer and get them to sort the mixtures out..one other thing..have you guys replaced the leads and plugs (plugs must have a smaller gap too)..before i did that i had the same problems as you..
also what gas consumption are you guys getting..mines anywhere from 16-19l/100km local..

[commsirac]

Muney, you have the same prob as me......only restarting troubles after it has been left between 20mins and 2hours?
As I said, the car has been recently serviced at a specialist lpg workshop, both plugs, leads and all mixtures were checked calibrated on dyno and on road.
For interest,lpg consumption at 110km/h is 9.5L/100km and daily suburban use averages at 15L/100km