Disco LPG problem cutting out

Hello all, im new to this site and im after some advice on LPG systems. Currently I have a problem when running on LPG. When switched over to LPG it idols lumpy and hunts a little. When driving it's fine but when pulling up to junctions it sometimes cuts off. I've had some advice from RPI engineering and apparently I need a complete ignition system upgrade for £425 which seems a bit excessive.

Has anyone else had this problem? Would be grateful for any advice.

Thanks
Gary

Hi Landy1, Sign up to LPG Discussion Forum • Index page and ask for advice on there, as there is a lot of knowledge & experience on that site. Hope you get it sorted as cheap as possible.

Thanks Planny

Hi, I once had a similiar problem to you, Next time its doing it whilst idling, put your foot just fractionally down on the pedal just enough to save it from dieing and see if the problem stops.

if so here are a couple of simple things you may want to try.

1: pop the bonnet and ever so slightly tighten your accelerator cable (turn the black plastic adjuster thats round the cable by hand) this will increase the revs slightly.

2: turn the adjuster screw on the vapouriser (if you have one) ever so slightly to make the mixture go in quicker/richer.

I think whats happening is on LPG on idle its not quite getting enough of whatever it needs to keep idling and just before it cuts out the automatic choke kicks in saves it but then the revs drop, the choke kicks in again (hopefully in time, otherwise you stall) and the hunting you describe occurs.You could also drain the vapouriser and change the filters in your LPG system. Also check for any tiny holes in the LPG pipes that could be letting extra air into the system, (probably after the vapouriser)

Also worth mentioning is the fact that a V8 LPG systems ingition components have to be in tip top condition to funtion correctly, I would suggest a change of plugs (same again unless someone with more knowledge advises you otherwise) some magnecore blue HT leads a good coil and maybe a new dizzy, or at least rotor arm. And of course you need a seperate advance and retard ecu for when your running on LPG (and a higher volt spark)

As mentioned above your probably best off going to the LPG forum to get a lot more info and probably the correct answer as I can only speak from my experiences with my LPG system but my fixes were shown to me by a LPG fitter (quickly sorting it out on his tea break) and this was about 3 years ago and its been fine ever since.

make sure ALL the ignition system is up to scratch ! timing needs to be altered to get the best from LPG conversion , will then be a tad lumpy on petrol . I'm assuming your disco is 3.9 or 3.5 .

Its a 1996 3.9 EFI with Multi-point system, the system was already on when i bought the vehicle so know very little about it. I believe its 'Metano' system?

Drove it to work and back today was ok when coming up to junctions etc, it seems to have good and bad days which is odd.

mrnice thanks for the info do you know where i would locate the vapouriser? I notice youve got the RPI A&R power amp and magnecor leads etc, do you feel this made a big improvement?

Hi, all my stuff was already fitted so I couldnt say if it made a big improvement sorry, im only repeating what the LPG fitter told me but He told me to run both LPG and petrol smoothly I needed the RPI A&R. The cars timing is normal when running on petrol and then when you switch it to LPG the RPI power amp kicks in and adjusts the timing to run on LPG, again im only going off my system (single point).

As for the leads, I got mine cheap so to me yes they were worth it but others would say at that price your best off using good normal ones and simply change them regulary, ive had mine on for quite some time now and they seem in really good condition still, the LPG fitter told me they were good leads to have as I was running on LPG.

If you have multipoint I dont think you have a vapouriser but im not too sure. I only have a single point system fitted. You will have to look on the LPG forums. Sorry buddy.

I found a safety check report from 2003, doesnt tell me much but its aparently got a 'Zavoli' front end.

Ive spoken to an LPG company in Petersfield he can take a look and do a service for £50 which sounds good to me only problem is he is booked up for the next 2 weeks.

It looks as though its worth investing some money into the igntion system. Currently i have underslung tanks but plan to replace them with a large tank in the boot to use for off-roading so best getting this problem fixed first.

Thanks again for the info

landy1 said:

LPG company in Petersfield

Click to expand...

Who is the company? I am just down the road in Havant and could do with someone local.

This sounds similar to my issue. Stalls when the accelerator is released from medium to high loads Mine's a singlepoint and now you guys mention it, it IS more like a fuel problem - my ignition system is as good as I can make it - rebuilt dizzy, RPI ignition amp, timing correctly set, new plugs and magnecor kv85 leads. My base idle is set fairly high ~950 rpm and yet it still dies. I've checked all the breathers, filters brass restrictor and cleaned the IAC valve to no avail. Does anyone have any information on the vaporiser? I wouldn't know which screw is the adjuster screw.

alexdon said:

Who is the company? I am just down the road in Havant and could do with someone local.

Click to expand...

Hi the company is P.I Fuel Systems

P.I.Fuel Systems Ltd - LPG Conversions

sidewaysste said:

This sounds similar to my issue. Stalls when the accelerator is released from medium to high loads Mine's a singlepoint and now you guys mention it, it IS more like a fuel problem - my ignition system is as good as I can make it - rebuilt dizzy, RPI ignition amp, timing correctly set, new plugs and magnecor kv85 leads. My base idle is set fairly high ~950 rpm and yet it still dies. I've checked all the breathers, filters brass restrictor and cleaned the IAC valve to no avail. Does anyone have any information on the vaporiser? I wouldn't know which screw is the adjuster screw.

Click to expand...

My adjuster screw I turned whilst the engine was on, you can notice the difference in revs (well I did) when you turn it so you will know which one it is.. it was on the top, the drain screw is on the bottom.