LPG

[Chris]

Hi All,

I've just has my astra converted to run on lpg - well 1000 miles ago. It
works well, and has a 'flashlube' system fitted which lubricates the valves
as LPG is a dry fuel compared to petrol.

I was just wondering, does any1 have a factory fitted vauxhall lpg system,
and does it have a similar flashlube system fitted?

Ta

 

[Ian Hatten]

Hi Chris

I have a factory fitted LPG system fitted to my 2005 Corsa 1.2. I have had
it since new and it does not have any flashlube system. It will be 2 years
old in a couple of weeks and has covered 48,000 miles with, touch wood, no
problems at all with the engine running. Filling the tank is a different
kettle of fish though and very inconsistent.

Ian

 

[Chris]

Hi Ian,

I was a little surprised when I found out that the flashlube system had been
fitted - as I thought that if the engine was designed to run on unleaded
fuel, then the valve seats were hardened and so would run no problem on
LPG.

Mind you the engine is the 1.6 8v variety, so perhaps, as this is an old
design, then the flash lube is in fact needed.

I've only filled up on LPG about 3 times so far - it was fairly
straighforward once someone told me how to do it.

What problems have you been having?

Chris

 

[Ian Hatten]

Hi Chris

I have a 48 litre doughnut tank in the spare wheel well. Taking the general
rule that you should only ever be able to fill it to 80% capacity that
should mean I would get a maximum of 38 litres when empty. The majority of
times when I have filled it when the car has actually run out of gas I have
only been able to get 33 litres of gas in before the pump shuts off
suddenly, but on one occasion I have managed to get 48 litres. Other times
when I still have had gas in the tank I have managed to get up to 45 litres
in. I have noticed when I do not get as much gas in the tank as I would
have expected the pump has shut off suddenly, other times when I get more in
it will slow down near the end. Lowest range I have had to a tank is 255
miles with the highest being 368 and it is practically all the same type of
driving, 80% motorway, using cruise control, and 20% A roads, so even trying
to use the range for filling up seems inaccurate for me. Car is still under
warranty but the nearest authorised LPG dealer for me will be 50 mile trip,
probably once for a diagnosis then another trip to get fixed if anything
needs doing. Overall I am averaging 38mpg on LPG and just got my tax disc
in at £15 for the year so definitely worth me continuing with LPG.

Ian

 

[Mike]

You will find that you get the most consistent fills if you use the same
pump. However the only way to get a good
idea of what you are getting to the gallon is to record all your fills and
mileages for a couple of months, then work out the average over that period.

when the pump shuts off suddenly thats the valve in the fuel tank shutting
off the inward flow of gas at around the 80% mark. But it can be a bit
variable, i.e. not too exact. If you let the gas run out then the float
valve that controls this (think of a ballcock in a toilet cistern) tends to
stick sometimes at the bottom of the tank, so no controlled cutoff. The
refuelling pumps are controlled by back pressure. If the valve suddenly
shuts at the right level then the pump suddenly shuts off, but if it has
stuck open then the pump will fight a slowly loosing battle against the
remaing space in the tank being compressed until it reaches its own pre-set
cutoff pressure.

But dont worry too much about it especially with an internally mounted tank
that isnt subject to corrosion (if mounted under the car exposed to the
elements) as the tanks have massive safety margins. They also have emergency
pressure relief valves as well, so all it would cost you is some money in
wasted fuel.

Mike

ex- 3.5l 86' range rover manual 21mpg on lpg
currently (laid up) 4.0 95' cherokee auto 17 mpg on lpg

 

[Ian Hatten]

Thanks for that Mike.
The average I have worked out is over the entire length of time I have owned
the car. I keep a record of this as it can give an insight into problems
that may be arising.
Out of 184 fill ups only 24 have not been from my usual pump, mainly because
it is up to 12p a litre cheaper than other places I can use.
The float valve could well explain another thing too. It has not happened
for a while now but sometimes after filling with gas the fuel gauge would
take a good 15 to 20 minutes to register back to full. It was one of these
things I was to pop back to the garage with when it happened to let them see
it.

 

[Mike]

If you have to pay for the float valve being fixed then dont bother-its more
trouble than its worth. If you do have it done then run the car out of lpg
before it goes in, as they have to depressurise and open the tank to get at
things. Going in with a full tank of gas is just wasting a full tank of gas.
But the float-as you have deduced-also works the fuel guage. Some tanks also
have an analog guage on the tank itself and if you can see this while
filling it will tell you if the valve is stuck, as the needle will not move.
Usually hitting a bit of a bump is enough to dislodge it.

Mike