factory fitted LPG on the LDV were fitted with a 70lt torpedo tank with an 'in tank' high pressure fuel pump.
This basically is a Bosch fuel injection pump fitted to pump lpg while still in liquid form and not in gasious form. Hence, the system is a 'wet' feed or 'liquid feed' system unlike non pumped systems which are gas fed and don't need a pump.
Becuse the bosch pump was originally designed to pump petrol, the aditives in petrol contain a lubricant which supports the pump. LPG does not have this lubricant and after a while the pump bearings run dry and become subject to friction which in turn 'slows' the pump down and reduces the pressure. In turn this starves the engine of the correct amount of gas, specially when the engine is under load and requires more fuel. Many engines will run on tick over but not under driving load when switched to lpg. You may be able to help this by pouring red X into the filling nozzel before you fill up at the filing station, The gas filler pump will force the RedX intothe tank where it will harmlessly mix with the fuel and lubricate the pump. If you are lucky, you may 'free off' the previous friction points within the pump. If your engine 'hunts' or 'races'and then 'hunts' it may be due to poor vacuum hoses or a slight air leak in the fuel line which allows air to be dragged into the system making it 'lean' then 'rich' in spasmodic fashion. These leaks are very hard to find as they can change with outside air conditions and engine temperature. You can find them with a tin of easy start. Systematically spraying each joint/hose. If your engine changes note then you have found the problem. gently move hoses as you spray to expose splits and leaks. Finally, if you are likely to run out of gas, stop the engine, remove the rubber cover by the ash tray in the center of the dash, remove the ash tray. inside on the left down about 3" is the switch which will be lit when the lpg is on and turn it off. Restart the engine which will then run only on petrol. Running the gas cylinder dry will cause the lpg pump to burn out or seize up because it no longer has liquid to pump. remember these are WET systems and react differently to vapourised non pumped systems.
FRED, March 2013
