LPG problem

[jiginc]

My Discovery 1997 3.9 is fitted with a DIGITEK DEG500 It should, and has for the past three years, started on petrol and switched to gas when the RPM went over 2000 rpm and then fell back.



Now it starts on petrol and within 5 seconds switches to gas. It will then run OK until reaching 2000 rpm when it switches back to petrol. The revs fall back and it again switches to gas this continues until I select petrol from the switch, thereafter it will run on petrol OK. This happens regardless of the load and will do it even when in neutral.



Does anyone have any ideas as to what can cause this or does anyone have any details of this system and how it is supposed to work



The problem did seem to happen following a fill up and I am waiting for the tanks to empty fully so I can use my usual supplier to make sure it’s not the LPG however I do not think the fuel will be the problem.



As said above any details of DIGITEK DEG 500 system operating or user manual would be very welcome.



Regards,



jiginc

[jiginc]

OK so no one has a Digitek system but how do you switch over from petrol to gas?

[jjsaul]

Ours has a manual switch on the dash.
It is Left for gas, centre for no fuel and right for petrol.
The centre postion is for changing from petrol to gas as you have to allow the petrol in the carbs to be used up before it pumps gas through, otherwise you get lumpy running and black smoke for up to 3-4 mins....yes, it's amazing how far it will go on what fuel is in the carbs....

It has 5 LED's.

1 is lit when we are running on petrol.
The other 4 are for LPG and act as the guage, ie: 4 lights full, 1 light nearly empty...

Sounds like you have a fancy high tech system, i think ours just switches on and off the relevant fuel pumps.

HTH, cheers,

[jjsaul]

i have found a photo of our switch. its the little black box just above left of the top of the gearlever.

sorry about the quality, and i'm not going outside now (1.45 am) to take another :rolleyes:

will take a better one if i remember tomorrow.

also ignore the wires, i was fitting a stereo at the time...

[Michelle]

mine just has a switch, when I wish to go from petrol to gas, I have to go to a neutral position first, allow the car to stutter, thus run most of the fuel out of the...(whatever it's in, I'd have said 'carbeurettor only apparently it doesnt have one lol...). THen flick to gas. Usually cuts out and I usually have to restart it and it's a manual thing, I choose when it occurs not the car. Going form gas to petrol is much simpler as the gas evaporates much more quickly and doesnt interfere with the combustion of the petrol, so I just have to flick the switch straight from lpg to petrol, no waiting in the neutral position.
My car exhibited similar symptoms to yours when running in gas, obviously being a manual switch it doesnt swap between the two fuels as yours has been but mine responded by backfiring instead.
I had to have the engine tuning checked and was required to buy new gas compatible leads (LPG requires better current) , new spark plugs (LPG requires more spark to ignite), and a new rotor button in the distributor. It fixed the problem.
I still very rarely get a funny thing where it wont start up properly on gas, but have narrowed that down to a particular gas station I used occasionally, which I use no longer (t hough I didn't know you could get dodgy batch of LPG the same way you sometimes do with petrol).