• Welcome to the Land Rover UK Forums

    You are currently viewing the site as a guest and some content may not be available to you.

    Registration is quick and easy and will give you full access to the site and allow you to ask questions or make comments and join in on the conversation. If you would like to register then please Register Now

Petrol Engines Poor Cold Starting on LPG

Malcolm Tent

Malcolm Tent

In Fourth Gear
My V8 (OMVL R90E, single point, open loop, twin SUs) has developed an annoying fault from a cold start on LPG. It actually starts as well as it always did, drives fine for about 300 metres then seems to be suffering fuel starvation and the power drops right off. After a couple of minutes it will run perfectly. I've checked the coolant level and there doesn't seem to be an airlock. There is no sign of the OMVL icing up. Could there be an internal fault with the OMVL? Or a sluggish solenoid? It's only been fitted for about 18 months, so I wouldn't have thought anything could have gone wrong this quickly? The ignition system is in good order, and once slightly warm the vehicle goes faultlessly.

I took it to my favourite LPG installer and he said it was running perfectly and there was nothing he could do to it without seeing it cold (which wasn't possible as it was too far from home to leave it there). It has only ever been approximately tuned by me, as I can't find anyone with an EGA machine and knowledge of LPG systems to properly tune it in the Cardiff area.

Any advice would be welcome on where to start looking for a solution.
 
For tuning, see my article on tuning - you can make your own poor man's analyser with nothing but a bit of pipe and a lambda probe.

I'm struggling to think what would fit your symptoms, but I do wonder if it is a coolant issue. Perhaps it is icing internally, but then clears - that might be hard to spot as it would clear in the time it takes for you to pull up, pop the bonnet, and take a look.
So a couple of questions : is your antifreeze up to full strength ? How is your coolant plumbed ?

Personally, on a continuous flow heater system like LR use, I always plumb the heater in series with the reducer - I never put them in parallel. That way you are pretty well guaranteed to get good flow, and you'll know if it ices up as the heater will go cold.
 
I had a similar problem on my TR8 with the omvl vaporiser, I found pulling the choke out (it's also on SU carbs) so the idle speed is higher for the first half mile or so fixed it (was idling around 500rpm when cold), It seemed to be that the vaporiser was getting so cold it was not vaporisng properly and flooding the engine, it would also be a pig to start afterwards unless I switched the LPG and petrol off, started it, then flicked the LPG on.
 
Another issue is that if you've never drained the heavy ends, when cold they are "quite thick". As they are sat on one side of the low pressure diaphragm they will interfere with proper operation until the reducer warms up.
 
Thanks to all for the suggestions. I can't see a problem with the heater circuit, so I'll take out the OMVL when the weather improves and check it for heavy ends or anything else untoward.
 
No need to remove it. With the system warm and the engine stopped, unscrew the small black plus that should be at the bottom of the reducer - it takes a hexagon key internally. Catch any 'orrible stinky black-grey sludge that runs out - and trust me, it is orrible and stinky.
There should be a small dribble - think less than an egg-cup. If there's more then that may have been your problem and you should try it to see if things have improved.
 
Back
Top Bottom