Full time LPG

[31satara]

Originally Posted by 31satara

Classicswede - My system always starts on petrol then I switch it straight to LPG by blipping the accelerator. I would be interested to know how to start it on LPG just in case I have any problems with the petrol side of things. The system was supplied by Mike and fitted to a different 740 before I transferred it to my 1990 B200E. It is an open mixer system but I don’t know the exact details – the switch has the bottom LED flashing on start up, then when revved and switches to LPG it goes solid. (Alternatively the switch can be used to change to petrol (solid red LED) – either before starting or whilst running on LPG). Hope that makes sense!

Following my earlier question the problems with the petrol system have arisen! (It may be due to the car now standing with just one run a month). Today it wouldn't start on petrol so I tried classicswede's method to start on gas but couldn't get the gas LED to stay on with the ignition on and whilst starting. Is there anything else I can do to get it to start on gas? When starting on gas should the accelerator be up, down or pumped...?
I've added an image of my switch if it helps (engine running).

[Mike B]

Originally Posted by 31satara

Following my earlier question the problems with the petrol system have arisen! (It may be due to the car now standing with just one run a month). Today it wouldn't start on petrol so I tried classicswede's method to start on gas but couldn't get the gas LED to stay on with the ignition on and whilst starting. Is there anything else I can do to get it to start on gas? When starting on gas should the accelerator be up, down or pumped...?
I've added an image of my switch if it helps (engine running).

Although I have a 740 with con/inj I havent been able to use petrol for two+ years [ must do it soon ] it started well though all weathers Takes 3 starts cold two hot every time , I put acc right down till starts , might be diff for you but might help .
Regards
Mike B

[john h]

My only local LPG station has its gas pump out of order, and it has been for a week. Sometimes it's very handy to be able to run on petrol...

John

[31satara]

Thanks Mike. How do you get yours to stay on gas before starting?

[Mike B]

Originally Posted by 31satara

Thanks Mike. How do you get yours to stay on gas before starting?

Hi John
It will not run on petrol after a big backfire 2+ years ago ,
Not bothered as it runs so well on Gas towed a caravan down to Plymouth , then Mevagisey [ ? ] then am now in Weston-Super Mare,
Home to Kings Langley Hertfordshire , tue. A couple of thousand miles .
My 740GLE is due for an oil change now ,as it has just gone over 100000 miles.
and now run in LOL.
It will not change to petrol anyway,
He is Constant Injection so not elect inj.
Hope this helps John .
Regards
Mke B

[classicswede]

From memory Mikes switch is for a carb engine so will start automaticaly on LPG every time.

If the lights on your switch are going off when cranking then the ignition live power supply is coming from the wrong place so could do with mooving.

Starting on LPG does often require light throttle but not pumping.

[31satara]

Hi classicswede. The lights don't go off whist cranking, but I can't seem to get the orange gas light to be on constant before or whilst cranking. I followed your earlier advice:
Turn on ignition, switch from gas to petrol, switch back (gas light should be steady), start.
However the gas light just continues to flash as I switch between gas/petrol/gas settings.
Any other possibilities? or is there any way to change it to gas only with a simple wiring change?

[classicswede]

You have the newer type switch there so to gas start you need to hold the switch in as you crank to start on LPG.

The only very short term way of getting the car to start on gas is by unplugging the switch a using a direct power feed to the gas solenoids (blue wire). If doing that you need to be extreamly carfull as gas will be constantly feed into the engine untill you disconect the wire. To start the engine that way you will need to start crancking as the power is connected.

If you have a long term problem and will need to start on gas on a regular basis (not just one off) then the best bet would be a change of switch to a carb type as per what Mike has and I use in my own cars that run and start on LPG all the time.

[31satara]

Thanks for the info. I hadn't thought of holding in the switch - I'll try that next.

[31satara]

That worked -started fine on gas. Thanks.