Fuel Loss

[cdraper]

I have an Elan+2 which is not used often enough!! When left in the garage about a quarter of a tank of fuel disappears every four weeks! The tank has been pressure tested - newspaper under the cat shows no trace of fuel - the inside does not smell of petrol!! Any suggestion on what next to check most welocme!!
Thanks in anticpation -- Chris

[rgh0]

Unless you have a teenage son or daughter short of gas for their car it sounds very strange, cant think of any other cause if you cant see or smell the loss !!

A plus 2 tank if full has a fuel level above the carbs and evaporation out of the carbs and replenishment from the tank by gravity could lead to a small loss but a quarter of a tank sounds far to much. My plus 2 does not experience any significant loss in the same circumstances

Rohan

[types26/36]

Chris,
Without external loss (leak or smell) it sounds strange, are you sure you fuel gauge
is accurate? maybe after standing for a while the gauge/stabilizer /tank unit is giving problems.
Brian.

[cdraper]

It is certainly not the fuel gauge - my wallet tells me the stuff is going somewhere - can it be anything to do with the vent system? By the way the car lives in a garage with several other - which do not suffer fuel loss - so do not think it is an envirmental problem
chris :unsure:

[1964 S1]

Hello, An environmental problem it may be... I have a 1969 +2 with Strombergs, in Ohio in the USA and must admit to the same problem. I've stored it outside 90% of the time and have parked it with 1/2 to 1/4 of a gallon of gas in it (YES I"M SURE) and then find it is OUT OF GAS a month later without ever having been started. Glad to hear someone else has this demon gas evaporative problem also. I was thinking gnomes. I have no fuel odors or physical drip leakage anywhere...

[Dave_Newcastle]

I have same problem too - fuel definately evaporates - I believe through vents under sills.

[cdraper]

Teenage daughters not the problem as they are the main users who complain!! It does seem others have experienced this problem - has anybody fixed it? I believe it is the venting system of the tank and that modern petrol "boils" at somewhere around 45?C. Petrol varies a lot through out the World and the "mix" can be changed up to six times a year - I am in Germany where there is often a quite high methanol content - destroys your feul pump as well!!

[type36lotus]

Heh, heh the other cars are in the dark of the night sucking your Elan dry. You might have vampire cars

Mike Geiger

[LaikaTheDog]

I have exactly the same problem, basically I loose a couple of litres a week, often my lotus is completely dry right through to the carbs. In the years that I have noticed this I have come to the following conclusion;
my fuel is evaporating via the breather tubes. But it only becomes a problem when the car is garaged, my garage gets relatively warm in the summer which I believe causes rapid evaporation. I temporarily reduced evaporation by plugging one of the gas expansion tubes out of the tank. But the problem just doesnt seem to be resolved, when I ran the car daily, this simply wasn't a problem...

[Gra-ham]

I have not had the problem to that extent, however when I first had my car I could always smell petrol in the garage. The garage lets wind in under the door and I realised this was blowing through the vent pipes. Being so large, 1 inch in diameter is sufficient for air to blow through. I fixed it by putting corks (wine bottle corks are a nice fit) in both when the car is stored. I forgot to take them out once, it didn't make any difference but I think I got pretty good fuel economy, mind I was only driving gently (running in), not over 3000 or so revs.

Graham
70 +2s

[cdraper]

Thaanks for those who pointed me in the direction of the vent tubes. A pity about ssome of the comments that had no added value! As a result of the vaarious suggestions I have plugged one side with 12mm bolt and sealer and done the same on the other - but witha 4mm hole drilled up the bolt. Of course I now cannot completely fill the tank - but so what. Will let you know if it works!

[cdraper]

After the best part of a month there has been no fuel loss with the vent pipe "plugged" as described. Thanks to those who pointed me in the right direction,
Chris Draper