GQ TB42EFI Dual Fuel will no longer start on LPG when cold or left overnight

[mudnut]

Hi mudnut, have checked all the electricals in engine bay, cleaned/re-grounded earths including the CP30 which I swapped over to another and checked coolant hose to the convertor. I even took bypass cover off and replaced the thermostat with a new one.

Once warmed up from cold start, the car will switch ok to the top gas setting from bottom petrol setting and run fine on gas all day. It also starts fine again on the gas setting as it always had, if I restart it within a few hours.However, the problem always resurfaces when I leave it overnight (it's parked outside) or for long hours off since the morning while at work.
It always starts fine on petrol when cold but not on the gas setting, where it will either start for a few seconds and then engine stops or it will not start at all.

Hopefully someone with the same set up as you sees your thread an can offer advise. I do know that over a long time the diaphragm goes slack and and the engine needs tuning. A neighbour's vehicle had all kinds of problems with wires that weren't crimped properly. Also spade lugs can feel tight but can get a layer of carbon under the contacts. I had to re-crimp all the conversion wires and use pliers to tighten the spade lugs before his car ran properly.