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Leaking tank or evaporation?

PostPosted: Wed Apr 10, 2013 7:40 pm
by jensmartin
Hi all!

I filled the tank on my +2 -72 in december and measured the petrol level down the filler neck with a stick. 3,5 months later the level had dropped 5 cm (2 inches). No driving of course :) Is this a leak or could it be evaporation? Seems like a but much to evaporate to me?
For what I can see, without having tanken the tank out, I can find no signs of leaks anywhere.

Any ideas?

Jens
Elan + 2 -72
Sweden

Re: Leaking tank or evaporation?

PostPosted: Wed Apr 10, 2013 9:59 pm
by bobm3142
The rate of evaporation depends heavily on how much the tank is ventilated. If you leave the cap off it will evaporate fairly quickley especially if it is warm.

If the tank has a leak in the boot then you would smell it quite easily.

Bob

Re: Leaking tank or evaporation?

PostPosted: Thu Apr 11, 2013 12:31 am
by Robbie693
Because of the size of the vent pipes, fuel in a Plus 2 evaporates a fair bit. It also smells a fair bit!

I'd bet on it being evaporation, if you have a leak it should be pretty obvious - stains on the garage floor, moisture around the tank, top of diff etc.

Some plug the vent tubes when not it use - do a site search for whiskey corks and you'll see some discussion about this very matter!

Robbie

Re: Leaking tank or evaporation?

PostPosted: Thu Apr 11, 2013 9:41 am
by Spyder fan
Hi Jens,
I agree that it is evaporation rather than a leak.

Question:
Why did you fill the tank if you were not going to use the car, apart from the waste from evaporation the octane level of the fuel will have deteriorated by now.

Here's an interesting article from BP regarding storing fuel. It suggests leaving the tank half full if the car is not to be used for a while and that fresh fuel should be added before starting the engine.
Petrol_Life_in_vehicle_tanksv4.pdf
(77.28 KiB) Downloaded 278 times

Re: Leaking tank or evaporation?

PostPosted: Thu Apr 11, 2013 5:18 pm
by jensmartin
Very interesting reading Alan! Thanks alot. So probably it's not a leak I have.
The BP document states that after 5 week 15% of the volume is lost! Seems to explain my lost two inches of fuel.

I've been learned that you should let the tank be full to collect less water when stored for a long time, this seems to be wrong.

Best regards
Jens

Re: Leaking tank or evaporation?

PostPosted: Fri Apr 12, 2013 2:45 am
by rfurzer
Not driven since December!

My +2 plots trouble if I leave her for more than a week or so.

The best place to lose the petrol is down the throats of the webers!

Russ

Re: Leaking tank or evaporation?

PostPosted: Fri Apr 12, 2013 7:26 am
by peterako
My +2 uses more petrol when stood still than when driving....

Evaporation...... :(

Would be more acceptable if the huge breathers actually allowed me to FILL the tank (tank evaporates less the fuller it is).

So, my solution is to drive it as much as possible.

It's more economical that way....at least that's what I tell 'er indoors...... :)

Lyka till,
Peter

Re: Leaking tank or evaporation?

PostPosted: Tue Apr 16, 2013 12:37 am
by h20hamelan
Evaporation

I am planning on newer teflon lines combined with steel or... along the length or backbone. As well as fuel injection clamps.

Rubber does allow evaporation and so do the +2's vent system.

There are posts to using a modern fuel breather vent (internals of a gas cap) While using the flip lotus external. You need to remove the spring etc. But it has been working on my car.


vote for 1/2 full/empty then fill and start. run empty and fill with fresh fuel