V40 faulty LPG sensor??

[psychobint]

I'm really hoping someone can help me on this one.

The problem started a couple of weeks ago when running the car (factory bi-fuel car) on LPG. All of a sudden the LPG gauge shot up to full reading yet I was aware that it should only be about three-quarters full.

It let me run out of LPG and then wouldn't automatically trip back to petrol as it thought it was still two-thirds full.

Now that it is full, it's reading empty and won't trip to LPG!!!

Has anyone experienced the same erratic behaviour from their bi-fuel car and if so, what's the solution please?

[classicswede]

Sounds like either a fault with the level sender or the in-tank float. Take the cover off the tank (big plastic nut) and see what the mechanical part of teh gauge reads.

[psychobint]

ok removed big plastic nut to reveal the gauge on the tank which was reading empty, Although i know the tank is full....
so removed the gauge from the tank but there is no physical connection of it to any sort of float in the tank....
so im now puzzled as to how it knows how much gas is in the tank...
could it be some sort of magnetic link to something inside the tank?
i have given the gauge a beating and got it to read 3/4 full so restarted the car the lpg gauge read half full and it switched over to gas no problem but after putting the boot cover back over it has dropped back to zero and now won't switch back onto lpg
so does it require a new gauge that fits external to the tank or is there something inside the tank that has gone a miss??? if it does work magnetically can i just strap a magnet to the back of it to test the gauge..
thanks in anticipation....

[classicswede]

You have sussed it. The electronic gause works magneticaly. You should be able use a magnet to move the gauge. If that works then it is most likely the float in the tank that is the problem. That will need changing by an installer.

If teh magnet does not work then the level sender will need replacing. (electronic part)