Thread: Starting on LPG when Cold

Not much help to your 101 but my RRc starts on petrol and automatically switches over to LPG once the revvs get over about 1K RPM.

As you know petrol vapourises better than LPG at low temperatures.

Do you have dual fuel and is your LPG tank open to the environment? Perhaps you could put a timer into the change over switch and similarly start on petrol. Another option for a tank which sits inside the tray, would be to make up a padded cover to wrap the tank, maybe even fit it semi permanent which will act as a sleeping bag to the tank and reduce the chance of the gas freezing.

You may not remember but at the AMVCS winter rally, I put my Primus bottle inside the Land Rover in a nylex cube with the bottle wrapped in special reflective bubble wrap. In the morning I had no trouble lighting my stove while most everyone else had no end of trouble, even resorting to rubbing the outside of their bottles. The reflective bubble wrap comes with the total perenteral nutrition every day and we throw it away. Some of our Club members have made fridge bags with the wrap inside. Am happy to send you some.

the P76,80's comodores-nissan-falcon-mitubishi ,EA/EB dual fuel AU and now a BFII Egas.
never had any serious issues with starting on gas when cold.
had refueling issues.

in the late 80's regulations-laws changed.the old push button electric gas primmer was outlawed and auto primer took over.with my VH commodore you could hold the button then crank over with the throttle held open.i practice this is probably a small bomb.

never seen a impco system with a working choke.a ramp lifted the diapham up and let the gas in.ive seen a few with air filters and ducting smashed due to poor spark.if the intake valve is open or the car has lots of overlap and burning is present the intake manifold gaskets take a workout.ive had to replace the gaskets and manifolds on a few cars.

it's mild temperatures here on the coast and I live on a river so frost is rare.I have been caught out in bathurst/orange area travelling through june long weekend and at guyra used to refuel when driving to glen innes.at glen we bagged the car.

the VK commodore struggled on petrol after the gas stopped,driving to sydney from dubbo,had to garbage bag the front end the trap enough heat to stop the carby freezing.told by the locals that with webber powered cars you forget about early mornings.

gas is already vapourised when it is mixed in the air flow unless you got a vapour/liquid injection system.it atomises better than petrol.thats the probblem-its too good.its ready to fire.the problem is its a dry fuel,so you often have reduced compression and you need a large hot spark to heat the plug gap.with the mitubishi[lean burn] the magna and lancer had to get plug swaps for cold starter motor starts.a quick run down a hill using the starter normally it would fire on a few cyls by the bottom.

you may require a flashlube,petrol or oil to get upper cyl lube during cranking.thin oil in the crankcase helps but Rover V8-leyland p76 often needs a heavier oil to help with glazed bores.

then once you got it started you need water being forced into the convertor[vaporiser].the unit needs to be in the bypass circuit and not T into the heater.some recomend those electric booster pumps and ive not used these and its rare to see them.the older falcons needed these as the heater and lpg didnt realy work at the same time.the AU freezes up if you dont let the car warm up i havnt had problem with the BFII but its best if the a/c is not turned on.

for years i planed to make a 240 preheater.i havent even got around to fitting electric water pump and i wondered what it cost to run a jug element to warm an engine.
its easy to get core plug heaters from canada but in 110V 800W.englsh version have been out of my price range[kenlowe] fire trucks have these,they plug into the power.VW/BENZ ambulances often have diesel preheaters,you see these on the left front with a 25mm exhauste ot behind the front wheel.toyota has a 800W12V heater[PTC] with the heater core.these modern engines dont make enough heat in cold weather--Jeep has a belt driven viscous pump to heat the manifold and passengers.

Garry when was the last time your 101 had a kit in the gas convertor. ?
Impco systems usually start well if everything is in good order.
One of the first signs of a gas convertor needing a overhaul kit is hard starting on a cold morning.
What happens is tar and gas by products build up in the gas convertor over time.
On cold mornings this tar is rock solid and stops the diaphrams and valves from working correctly in the gas convertor.
If you get the motor going and the motor warms up ,the hot coolant water flow warms the gas convertor and the tar turns to a liquid allowing normal running and starting.
About every 4 years is a good time to replace a gas convertor or to put a overhaul kit though it with a vehicle in normal use.
There can be many other reasons for hard cold starting on gas like if the gas components are not correctly matched to the motor, vacuum leaks and reduced spark because for greater battery cranking loads etc.
Nomally on a well sorted gas system the only problems very, very cold weather can do is cause the gas convertor to freeze up due to the motor taking longer to warm up and therefore warm the gas convertor.
My experience has been electronic gas lockoff controllers and primers are much better than old vacuum switch set ups.
Gas convertors with hand primers are good , but it needs a good operator and someone who knows that particular vehicle to get the best out of it.
I work on forklifts every day running on gas and every day they start and run on it as very few forklifts will dual fuel.
Winter to me means I fit gas kits and batteries.
summer blocked radiators and new hoses.
No rest for the wicked....

Originally Posted by garrycol

How do you start LPG only systems on really cold mornings.

My 101 is both LPG and petrol and anything below about 5 degrees it will not start on LPG - and I have a direct gas injection starter that squirts LPG direct into the inlet manifold bypassing the carbies etc - below about 5 degrees no gas comes through.

As I have to start it up at about 7 in the morning and expected temp is going to be about -5, I have been out running it on petrol to ensure the carbies will be full of petrol in the morning. If I stop on gas and then the next morning try to start on petrol with the carbies empty it is also hard to start on petrol.

So - how do you start LPG only systems on really cold mornings???

Garry

The primary problem on cold starts is the cranking speed of the engine is lower, due to a cold battery and increased oil viscosity. If your primer system is hooked up to the starter relay, the amount flowing into the manifold will drown the engine during very cold starts.

With Impco sytems the best way to operate the primer is to have a separate button for it. Then you operate the starter, as soon as the engine is cranking you then press the primer until the engine starts. That way you can always vary the amount of gas going into the engine to suit the occasion. The window for correct mixture to fire is narrower when cold. As I have said before, straight gas cars should start with frost on the bonnet, the trick is to get the starting mixture spot on.

Also ensure your plug gaps are not too wide, a maximum of 0.7mm is recommended for LPG starting. Otherwise cold damp air will cause tracking from the slightest patch of dirt anywhere near the dissy cap contacts.

Another possible solution is to have some kind of heater on a time clock to warm the engine bay for 1/2 hour before starting. People I know had an old bulb style lead light they left under the bonnet overnight. Once I replaced a few things this became redundant. Making sure your cranking batteries are A1 is not to be neglected.

Originally Posted by 101 Ron

Garry when was the last time your 101 had a kit in the gas convertor. ?

Mine is all less than 12 months old and travelled less than 10,000km.

The converter is a brand new impco and the mixer was rebuilt 12 months ago.

You remember up in Abercrombie last year it was hard to start in the morning - was because I had run on gas the day before and didn't swap over to petrol before stopping the night before. On start the next morning (water froze inside the 101 with me inside) the carbies were empty of petrol but most likely a little gas still in the inlet manifold - when starting like that it was trying to run on the bit of gas remaining and petrol and the mix is too rich - remember how it was blowing black smoke just before it started to fire up.

I now have the routine down pat - if the start is below about 5 degrees no gas comes through on start (even through the direct injection system) so petrol is the go but it needed to have been on petrol at shut down for an easy start.

If starting was so easy on LPG why do most still start on petrol if it is not necessary.

So back to the original query - on LPG only systems is starting when very cold an issue and how do you get around it.

Originally Posted by bee utey

The primary problem on cold starts is the cranking speed of the engine is lower, due to a cold battery and increased oil viscosity. If your primer system is hooked up to the starter relay, the amount flowing into the manifold will drown the engine during very cold starts.

With Impco sytems the best way to operate the primer is to have a separate button for it. Then you operate the starter, as soon as the engine is cranking you then press the primer until the engine starts. That way you can always vary the amount of gas going into the engine to suit the occasion. The window for correct mixture to fire is narrower when cold. As I have said before, straight gas cars should start with frost on the bonnet, the trick is to get the starting mixture spot on.

My gas primer button is not connected to the starter system and is only plumbed into one carby manifold not both. I normally give it a squirt for a second or two before start. You can normally hear the gas flowing but not on very cold starts. Actually when on petrol - a little squirt of gas when starting on petrol for a normal start makes the start instantaneous.

In agree that when it does not fire straight up having the button pressed is a bonus - however there is no gas below about 5 degrees.

Cheers

Garry

Originally Posted by garrycol

So back to the original query - on LPG only systems is starting when very cold an issue and how do you get around it.

Propane liquefies at minus 40C. So there will still be pressure to run at -5C.

Dismantle the primer solenoid and clean it of the waxy stuff. Or purchase a can of aerostart, run a vacuum hose into the cab where you can squirt a bit in when you need it, then plug it again. A vacuum gauge port?

If starting was so easy on LPG why do most still start on petrol if it is not necessary.

Simplicity. Mixer type EFI systems start on petrol because the injectors are right at the head and fire a small amount of petrol for quick starts. The possibility of backfires is reduced. Many dual fuel cars eventually lose their petrol pumps due to age and they still start, just takes a few seconds longer.

Emissions: Cold LPG systems are less stable than petrol systems so gas injection usually warms to 30-40C before switching over. Manual override is provided with most injection systems and they start no probs on gas only, just the idle is a bit rougher sometimes.

E-gas Falcons with gas mixers start on straight gas all the time. If Ford can manage it so can everyone else.

Originally Posted by bee utey

Or purchase a can of aerostart, run a vacuum hose into the cab where you can squirt a bit in when you need it, then plug it again. A vacuum gauge port?

Was already thinking about that.

Wasn't as cold as predicted this morning - just 0 degrees and it started first go as I had run it on petrol last night so that the carbies were full of petrol.

Cheers

Garry