Intermittent Power Loss

[Raggylad]

1983 Land Rover 110 V8 running on original carbs (Solex) and single point open loop LPG system. Runs absolutely fine on petrol.

LPG system has been completely reliable for the 3 years since installed - until recently. While it runs fine 99% of the time, twice in the last 3 weeks (and about 1600 miles) it has faltered after switching from petrol to LPG.

It will switch over to LPG fine, but only runs normally for a couple of hundred yards then suffers a radical loss of power and eventually dies - unless I switch to petrol, when it picks up & runs normally. There is no obvious misfire; if it were petrol, I would suspect fuel starvation - but with LPG ... ? Trying to switch to LPG a second time results in immediate power loss.

Ignition system is fine. Plugs, rotor arm and distributor cap were all replaced at last service a month ago; leads (Magnecor blue) are 18 months old; distributor has Aldon electronic conversion module and there is a healthy spark at all plugs.

The only common factor to both times this problem has occured is that both times it has been the day after a long run (Wiltshire to Argyll and Pembrokeshire respectively) towing a boat.

As I said, most of the time, this does not happen; intermittent problems are a s*d. Any ideas ?

Many thanks.

[Quagmire]

I doubt this would give you an intermittent problem, more of a continuous one, but:

Have you checked the filter on the LPG? Mine gets dirty (with a grey looking dust) every 6 months or so. Last time I changed it out the mixture became quite a bit richer afterward...

How quickly is it dying? Could it be that the LPG switchover gear is losing the signal from the ignition telling it that the engine is running- therefore causing the solenoids to close? Mine will run for 3 seconds (default setting) after losing the signal from ignition before the valves close down.

Or could you be losing any water, preventing the vapouriser from well, vapourising?

[ChrisJC]

I found my vapouriser had a lot of oily gunge in it at one time, which can't have helped.

But it sounds like a problem with one of the fuel shutoff solenoids to me.

Chris.

[Raggylad]

Thanks for the replies.

LPG filter was changed and vapouriser cleaned out during the service a month ago. No problems with water loss.

The engine running signal sounds worth investigating, though; good idea. It can, however, be much longer than 3 seconds before it dies. Might be a dodgy electrical connection somewhere there ? I'll check.

No problems at all today - typical !

[ChrisJC]

I have had an odd problem where the solenoid on the vapouriser seemed to fail to open properly. I dismantled, cleaned it up, and away we went for a few months.

But it wasn't intermittent, when it played up, it wouldn't run on LPG at all.

Chris.

[Raggylad]

Wiring all seems to be OK. I'll try cleaning up the solenoids. Problem is still there .... occasionally.