...Either a filter clogged, vapouriser problem or some other restriction causing the fuelling on LPG to have changed from the state when it was set up.
The multivalve failed whilst I was away last year, and I had it replaced at the local BRC agent (the tank is BRC).
The new mulitvalve had two problems: it reads incorrectly on the motorway i.e. if the fuel is consumed fast (it only drops to two out of four green leds when the tank empties) and it regularly gives false "trips" (sets off the empty buzzer) even when full.
I took it to the original LPG fitter in Battersea and asked them to change it. They maintain they did, but I still get exactly the same symptoms
Could this be the cause of an LPG metering problem?
We might be onto something here.
False trips occur when the vapour pressure falls too low for the engine to continue running on LPG.
Give that the multivalve is what caused this problem it would make me wonder if it's not capable of flowing enough liquid to feed the engine. If this is the case, it might well be causing the engine to run lean, and hence trim the fuel to the point where starting becomes awkward.
Gauge readings could well be because a different multivalve has been fitted without the display being calibrated to suit it.
Issues if the fuel is consumed fast make me wonder if the pickup has fallen off the multivalve. In this case, the valve will be delivering vapour instead of liquid. This restricts the flow of fuel causing a loss of pressure (see my first paragraph!) and, if the gas is being consumed quickly, the temperature of the tank can fall so low that the gas can't boil off vapour any more, so the system behaves as if the tank is empty while the liquid level (as shown by the gauge) remains high.
If you take it for a decent run (say a couple of junctions up the motorway at a decent cruising speed) then get out of the car and feel the tank, is it cold, and perhaps showing signs of condensation or frost on the outside? (it should stay at the same temperature as its' surroundings).
It would also be worth checking the temperature of the vapouriser at this point, to make sure that it is piping hot.
Kevin