[Public-List] SURPRISE came up with a new trick...

[Gordon Laco via Public-List]

Hello friends ­ here¹s the story of a new trick my boat came up with this
winter.

When laying her up, I did all my usual procedures, one of which included
filling the fuel tank with gasoline to eliminate air inside as far as
possible, on theory that this minimizes the formation of condensation.

I noticed when I was putting the tarp on in the fall that some fuel had come
out of the air vent in the transom.  The top of our fuel filler is slightly
higher than the air vent, so it¹s not unusual for some fuel to spill out if
the fuel filler hose is overfilled.   I assumed that while being moved the
boat may have been tipped aft and that may have forced fuel out the air vent
line.  I forgot about it.

Last Sunday I rolled the tarp off.  Yesterday, my friend Rod (hello Rod)
texted me from the marina to report that fuel was coming out the air vent.
Hmm, thought I.  Maybe he¹s just seeing the residue of what happened in the
fall ­ and I¹d checked several times during the winter to make sure hadn¹t
happened again...)  I texted ³old dry or new wet?²    He sent back the bad
news, wet, and dripping.  We both assumed water had got into the tank and
was forcing the fuel out.   Crikey.  (actually that¹s not what I said)

I went over to the boat and sure enough, fuel was dripping steadily and was
all over the ground under her.  While driving over I ran through what might
have happened that would be easier to resolve than the water theory.  I knew
that since the old metal tank in my boat was installed at the factory with
the forward end several degrees low, and the filler and air vent fittings
are on the forward end, there is always a wedge shaped air void in the after
part of the tank when otherwise it is full.  That air has no access to the
air vent for relief.   I surmised that as the boat warmed up, that air,
saturated with gasoline vapour, may have expanded and developed
pressure...and that may be what was forcing fuel out the air vent line.  So
why was it only dripping?  Because I¹d installed a spill inhibiting device
in the vent line which was only partially preventing liquid from
escaping....  These were my thoughts while driving.

I opened the #2 tank¹s deck plate, the plastic saddle tank which had the
water problem last year.... No problem there. No air pressure; fuel level
still normally below the top.  That told me the issue had to involve the old
metal #1 tank I¹d possibly overfilled.

The instant I started opening the deck plate, air began hissing out under
considerable pressure.  The instant I reached the end of the screw, the cap
flew off with a gush of air and about a cupful of gasoline spat out; there
was a gargle, and the remaining fuel drained back down the filler hose.   I
looked over the stern and saw the steady drip had stopped.

I closed things up again, poured soapy water all over the deck and the
ground beneath the boat, scrubbed the fuel residue off the transom and was
much content.  Rod arrived and I thanked him for telling me I had a problem.
I¹ll thank him again...  Rod, thank you!

I got home for supper and told my son Rob - ³I wish it hadn¹t happened of
course, but I¹m very glad my friend reported this to me.  And how often in
life does one have a crisis, develop a worse case and best case diagnosis
... And find the cause was the Œbest case¹ scenario.  How wonderfully
satisfying.

Gord #426 Surprise