Please please help, grand voyager 2000 lpg problems

[u2opia]

I am a total newbee to lpg, i have just aquired a grand voyager yr 2000 3.3ltr.
it has lpg fitted which i know nothing about, nor do i have any idear on where to start. all i know is the system was fitted in 2004 and its called a sequential gis (bigas) and the tank is fitted under the floor.
Now my questions are, how do i know if the car is running on lpg or petrol at any given time, i dont even know how to engage the lpg system if at all.
How do i know if the tank is full?? i tried today to fill it but the dashboard switch(press button) was showing what i think was empty, but when i tried to fill it the pump kept stopping and i had to keep restarting the pump, How do i find out what size tank is fitted, this should give me some idea on when the pump is acting up or the tank is actually full. now with it being a sequential system i think i have read somwhere that it automaticly switches to lpg on its own???? being a novice to lpg this dont sound right to me but hey what do i know.
The dashboard display is oblong, about 4/5cm in length by about 2cm in hight, on the left it has a G with an LED below it, on the right it has a P also with an LED below it, inbetween the two is a button, above all the way across is LED's, now when i start the engine the led below the p is illuminated red, and unless i press the button in the middle thats how it stays even when the car has run for a long time, now if i press the button while the car is in motion all the led's go mental, they all flash and an allarm sounds, so i stop the car and press it again the led under the G flashes green for a while and then becomes solid, so i dive away, within a miniute or so all the led's right across the display at the top flash green and the alarm sound until i press the button again which then illuminates the P in red. now i put about £30.00 worth of gas in today but from the way the dislay is acting, it looks like the gas is empty, now this all could be down to me not knowing how to read the display, but after the last atempt to fill up(£4.36) i decided to fill the petrol tank up to full. now either the car is extreemly fuel efficiant or the gas is working but not showing its working, because as you know the fuel gage is set in incruments of 8 as apposed to full 3/4 half 1/4 and empty i did aprox 150 mile on what i thought was petrol only from full and the fuel gage had only moved to the middle of the 3/4 and last eighth line, which woul give me approx 7/800 miles per tank of fuel???????? great i know but why isnt the gas showing as working.
I know this is long winded but in order for you to help i needed you to know as much about the situation i found myself in as me.
Please
Please
Please
Please
Please
Please Help me.

[jpb53]

Try this linkhttp://www.vanmeenen.com/LPG-autogas-Vlaanderen/LPG-conversion-eng/LPG-conversion-kits/sgis-bigas-gasinjection.htm

[Robertmchenry]

You need to contact the people that installed the system, else try the link on the 2nd post.