Condensation in fuel tanks

After having had the bottom of the Duke's tank rot out very expensively,
I'm anxious to avoid it happening again.

! can't heat the garage, so that's out. What says the FOAK? Just keep
the tank brim full so condensation can't get a hold? Empty the tank and
spray lube or anti-corrosion stuff everywhere inside and just leave it
until summer? It'll smoke like a two-stroke on the first tankful, but I
don't GAF.

Suggestions?

 

Dunno. I've had the 30 year old Morini 2C tank sitting in a garden shed
about half full of fuel since late 2007. It seems to have survived the
experience. The fuel in it even started up the bike quite easily a few
weeks ago (now in the unheated garage). Perhaps Ing. Lambertini
specified sterner stuff for tanks than the Ducati peeps did or perhaps
the shape of the Ducati one promotes corrosion in little pockets that
harbour the water. I thought my old chemistry teacher taught me that
it's the oxygen plus water that does the damage, so inert gas filling
and sealing might be the NASA solution.




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Drain it & keep it in the house would seem to be the obvious choice.
Brimming it's a good idea in theory but impossible to do on anything
remotely modern. If it's a keeper, POR15 it so you don't have to worry
about it again.

 

My understanding is that brimming it helps to reduce condensation
forming, but it's a bugger to stop it completely, especially in these
temperature extremes we're getting right now.

I put some of that fuel additive stuff in when I can remember (s'posed
to stop the fuel going off) and try to keep the tanks full.

I'm pissed off to discover the paint starting to bubble up (on the top
of the tank on my low mileage VFR750 though.

The only realy answer seems to be either heated/dehumidified garage or
one of those air bubble thingies. Or regular use of course - can't beat
that. Unfortunately I can't do any of these.

 

Use Dri-gas or methanol occasionally to mop up the water content and
burn it.

 

I would have thought that a petrol tank would be full of petrol vapour which
would prevent any water vapour getting in, so if you have water in the tank
it got there via another route. Diesel OTOH does not form a vapour so easily
and is therefore much more vulnerable to condensation.

 

Not quite true. Petrol and water mix surprisingly well, so there's
always going to be some there.

 

Modern petrol contains Ethanol which which can attract and/or contain
water, so I'd drain the tank. You can get fuel stabilisers but no idea
how effective they are.

Iggy..

 

Ethanol attracts water? I now see where I've been going wrong.

 

Are you certain it was caused by condensation - as opposed to water in
the fuel?

 

You'll go blind!

 

I thought that was some kind of cleaning product to be used prior to the
"Italian tune up". How does it deal with condensation and water related
corrosion in fuel tanks?

 

Twice!

 

Good question. Answer: no.

 

I certainly share the worry of the condition of the 750SS (and my other
steel) fuel tank(s).

Draining, drying out and refilling with "known water-free" petrol is
what my over-wintering strategy has evolved to for elderly steel tanks.
"Known water-free" petrol? I've yet to see phase separation of "fresh"
ethanol-containing petrol, but agree on the view that the ethanol could
help absorbing water, at every stage of mixing it into the petrol.

I was thinking of extracting the ethanol from currently available
unleaded with a small amount of water, and use the resulting
ethanol/water-free petrol to keep the tank topped up during winter. No
idea if this theoretical approach would help in practice, though.

 

I know I only have a lowly 400 4 to worry about but this is my plan....
Get gallon tins full of ordinary petrol and let them stand for a few
days.
Carefully suphon the petrol so any water that has settled gets left in
the bottom.
Make sure the 400 4 tank has been emptied of as much fuel and/or water
as possible.
Fill right up with the new petrol after heating up the are where the
bike is so the tanks not sweating.
So there won't be bugger all space left for damp air to live in the tank
and I'll have got most of the water out of the fuel I'm putting in.

 

If youre going to leave the bike for any length of time, why not just
empty the tank into a can and leave the cap off. The tank can air, no
problem... Anthing longer than a couple of months the fuel will still
be fine, so will the tank. Its not rocket science...

Oh f%ck, I cant believe it, I just used logic...

O

 

Or just use some methanol/isopropyl alcohol.
http://en.wikipedia.org/wiki/Dry_gas

 

BS EN 228 allows for 5% ethanol to be used in the blend, which will have
similar properties. What you can't tell is whether the fuel you buy has
that content from day to day as it isn't mandatory

 

Ah. But if you have to keep your tank in an unheated space that is
subject to varying humidity and temperature you can (quite often) have
a situation whereby a steel tank is suddenly cooled whilst full of humid
air.
This gives you condensation within the tank which ends up sitting at the
bottom of the tank....