Now getting codes 0200 (injector circuit malfunction) and 0170 (mixture too lean/rich).
The symptoms are :
Car always starts without eml - when reving over 3k or putting engine under load (ie. going up a hill) the eml comes on.
Reving car at 3k for say 10 seconds - whilst stationary - the eml comes on whether I'm running on lpg or petrol. At 3k on lpg the engine revs smoothly, on petrol is seems to rock as if one of the cylinders is not working as the others.
The only thing that has changed is that I fitted a new thermostat and the engine is for the first time running at normal operating temperature.
Friend suggested that the fuel pump may be on the way out - anyone with any other ideas to try first as the pumps look expensive. I've discounted the injector as the lpg ecu sends a dummy signal to the cars ecu - so if the injector was totally shot, the engine would still run.
Any ideas appreciated.