I have a ba dedicated gas car with a vialle system the car was not starting so i
1 replaced the converter
2 cleaned the ring on the inlet manifold as it was dirty
3 replaced the stepper motor
after this the car started but would not run beyond 15 seconds when i turned the car off for about 1 min it started again only to do the same problem

I would appear that the fuel is not getting through from the tank or is it the o2 sensor or do i have to reset the stepper motor

If the stepper motor needs resetting can anyone tell me a simple way to reset it or is there a safety timer cut off in the system and if so where is it located and finally could the computer have an intermittent fault

Lpg seems to be a great headache

Can anyone who has had this problem help in solving this problem

Have you fixed your problem, or do you still need help.

Thanks for your question but i still cannot find the problem it starts for about 15 seconds then stops but wait a while then it runs again any idea if it is the computer issue or do i have to have the stepper motor calibtated .

Similar, not the same though.
auto-electrical-forum-f89/egas-ba-wont-crank-t131211.html

Was the car playing up on the highway and around the streets,
or did you park it one night and it would not start the next day.
Did you fit a second hand convertor on the car or a reco or new
one, and did it come with the lock off solenoids and primer, or did
you fit your old ones, and what tests have you done to solve your
problem. I assume you have turned the valve on the tank back on.
What made you go for the convertor and stepper motor, also when
you cracked the liquid line did much liquid gas boil off.

When diagnosing a problem like this I start with the electrical side and go from there.

Get a multimeter and check for power at the solenoid cut off switches.. one at the tank and one before the converter. make sure both are powered and switching when the ignition is on.

The O2 sensor failure will make it run badly, but shouldn't stop it as it will just swap to rich preset maps.

last time I fixed an issue like this it was actually a bad connection on the terminal of the cut off near the converter.. since falcons tend to have them above the exhaust heat kills the tension on the terminals and they become either huge voltage drops or outright open circuits. check the little stuff first.. much cheaper than just replacing things at random.

You were nearly right, the lpg relay, the tank lock off's or tanks if a ute, the idle solenoid as well as the convertor lock off, will not receive battery positive until the engine is cranking and the pcm receives a crank signal.

The prime solenoid has battery positive on it when the key is on, and the pcm will ground the solenoid when the engine cranks after it receives a crank signal, and the length of time depends on engine temp and time.

In a normal situation when the engine is cranking the pcm will pulse the stepper motor in to it's maximum position, then pulse it out to around 170 steps which is around the default position for open loop. While the engine is idling the 02 sensor will start cycling between .1 and .9 of a volt and the stepper motor will pulse in and out to keep the air fuel ratio at stoichiometric in closed loop.

Thanks I will ask a mate can i use his hoist and check the power to the lockoffs and especially the one at the tank Thanks it is not the o2 sensor it must be a wire issue or power to the solenoids

Hi just to Hopfully help some one out iv got a fg factory fitted lpg system in the ute and over the last 100k or so it became harder and harder to start and was using a lot more lpg than it should. The car then failed to start at all the engine would turn over just fine the engine would fire for a second or two then die, there were NO fault codes on the code reader.
I ckecked the lpg fuse and lpg relay next to computer all good.

I jacked up the ute and had the wife turn it over and checked that the tank shut off solonoids were clicking all good their
I then checked the solonoids on the converter and they also clicked
T
I then removed the 2 x 10mm drain bolts under the converter to make sure there wasnt any water coolant a very small amount of oil is ok but all good.
I then removed the intake hose to the throttle body had the wife crank the engine and sprayed quick start spray and the engine fired up for 15 seconds so all of the electrics plugs coils etc were fine
I then unscrewed the stepper motor which was only 2 months old to find the ram in the full extended position, i cranked the motor over and the ram was frozen and didnt move. So grabed the old stepper motor cranked it over and the ram worked fine. The new stepper motors ram had cut off the lpg from getting to the engine.
The car started first go with the old stepper motor
So this is something you may wish to look at if your having a similar problem