toyota hilux workmate 2.7, 04 model

Although many modern integrated LPG/ULP systems start on petrol then automatically switch to gas once the coolant warms up a bit, it is not necessary to do so. If the engine starts OK on gas, then that's fine. I would however recommend that you do use some petrol at least once a week. Even if it's for 20kms or so. Just helps to keep this lubricated and in working order.

As for the clicking noise, is it a once off click right as you flick the switch? If so, this would be the LPG shut off valve and the noise you're hearing is normal and healthy. If however it's clicking more than once or lasting for a longer period of time, it may require having someone look at it. Please provide more details.

There is always a clicking sound on mine when I switch from gas to fuel. Its the solenoid switch that controls the gas flow.
However,lLike the other post said, if in doubt get it looked at

Mike

My `96 V6 4runner was converted to Direct Injection LPG in May 2007. Its designed to start on petrol when cold. I was told why and the importance of starting on petrol when the motor is stone cold, but I have forgotten the reasons why. However, the way the system has been programmed, it does start on petrol when cold, and when the water temp has reached 55degrees C then it switches over to gas, when the RPM exceeds 1500. I also have the Flashlube installed, and that provides the cylinder head and all the moving bits inside with permanent lubrication, to stop valve seat recession. I dont know what system you are using, but there is no clicking sound when mine switches over.