[DeTomaso] Fuel tank ventilation - fuel spill
Will Kooiman
will.kooiman at gmail.com
Mon Mar 7 16:11:13 EST 2022
Or attach a PCV valve to the vent hose. Plumbed correctly, it will prevent a vacuum, and it won't let fumes escape.
Been there, done that.
On 3/7/22, 1:05 PM, "DeTomaso on behalf of Mike Drew via DeTomaso" <detomaso-bounces at server.detomasolist.com on behalf of detomaso at server.detomasolist.com> wrote:
Hartwig,
I think you've hit upon the solution.
That vent hose originally went to a charcoal canister, which
experienced vacuum from a second hose that went from the canister to
the air cleaner. The hose was higher than the tank. Fumes would be
neutralized by the charcoal in the canister.
Now your hose just goes to the ground. It will therefore just vent
fumes directly to the atmosphere, and if the tank is filled to the
brim, it may drool a bit of fuel onto the ground.
The obvious thing to do would be to reintroduce the canister to the
mix. Short of that, perhaps routing the hose so that it climbs a little
bit before descending might help matters?
I have a similar issue and my garage smells of fuel for a day or two
each time I drive my Pantera.
I like it. :)
Mike
Sent from my iPad
On Mar 7, 2022, at 08:31, HARTWIG ASSHAUER
<hartwig.asshauer at airbus.com> wrote:
Hi Mike,
I checked the interface between the vent and the top of the tank. There
is plenty of dust in that area and no signs of any fluid. I think that
interface is 100% tight. However, when shaking the vent hose, there are
fuel droplets dripping out.
Cheers
Hartwig
On Sun, Mar 6, 2022 at 10:28 PM Mike Drew <[1]mikeldrew at aol.com> wrote:
Hartwig,
The non-linear movement of the fuel gauge is simply explained by the
shape of the tank. It's not a simple box. Philosophically it's more
akin to a pyramid. Because it's much smaller at the top, the fuel
sender float sinks much more quickly at first. So your gauge will go
from full to 3/4 relatively fast. It will move a bit more slowly from
3/4 to half, and then at a constant (and arguably `correct') rate from
half to empty.
It's probably best to return to the canister system if you can, it
it's not strictly necessary.
Have you determined where exactly the fuel is leaking from? I always
assumed my tank was cracked near the top, and it would leak at least
one or two gallons immediately if I completely filled it, which led to
much embarrassment at the gas station. Eventually I realized that the
problem lay with the interface between the vent and the top of the
tank. The early aluminum tank is heavily reinforced where the filler
neck and fuel level sender attach, but inexplicably where the vent
attaches its very thin.
Mine had the vent attached and reattached several times which distorted
it. Although I considered various means of rectifying the situation,
because I happened to have a spare steel tank from a later car, instead
I just replaced it.
My aluminum tank has been at a Pantera buddy's house for several years,
awaiting us to get the energy to fabricate a reinforcing ring which
would affix to the inside of the tank and enable the vent to be
properly secured.
If you pop your gas tank cover off, fill the tank to the brim and find
gas pouring from between the top of the tank and the vent flange, that
just might be the impetus we need to develop a fix for you, using my
tank as the guide.
The problem is detailed at length in the April 2018 PCNC newsletter,
available to all at [2]www.Panteraclubnorcal.com
Let me know what you find out!
Mike
Sent from my iPad
On Mar 6, 2022, at 13:13, HARTWIG ASSHAUER
<[3]hartwig.asshauer at airbus.com> wrote:
Hi Mike,
Yes, my tank is wrapped in fibreglass. The car is from 1971 (VIN 1571).
When I bought the car it had the canister installed but there was no
vent hose connected to it and I removed the canister. The tank vent is
connected to a simple rubber tube that goes straight in front of the
left aft wheel. From the beginning I had noticed that the first quarter
(fuel gauge) empties quite quickly. I always thought that this is due
to the Italien non-precision instruments installed but it seems that my
car is equipped with a fuel jettison system. Should I go back to the
canister setup or is there a smarter way?
Cheers
Hartwig
On Sun, Mar 6, 2022 at 5:23 PM Mike Drew <[4]mikeldrew at aol.com> wrote:
Hartwig,
The vent hose originally ran across the engine bay beneath the rear
window, into a charcoal canister. Another hose ran from that
canister to the engine, although at the moment I can't quite
remember what the scheme was. Was the engine also vented to the
canister? Or was the canister providing vacuum that drew fumes from
the tank, through the canister and into the engine, as modern cars
do?
In any case, if you disconnect the vent hose from the canister and
instead just point it at the ground, in certain rare circumstances,
when the tank is completely filled, it can actually siphon the
engine tire contents onto the ground! (I've only heard of that
happening once).
My car had an aluminum 1971 tank in it and used to dump fuel all the
time. I discovered that the top of the tank where the vent is
attached was very thin, and it was distorted by the attaching
rivets, preventing a proper seal. As the vent is below the top of
the tank (which is stupid), it is submerged when the tank is
completely full. I know you have a 1971 car--is it early enough to
have an aluminum tank also? (They are wrapped in fiberglass,
ostensibly to prevent leaks).
Mike
Sent from my iPad
> On Mar 6, 2022, at 07:41, HARTWIG ASSHAUER via DeTomaso
<[5]detomaso at server.detomasolist.com> wrote:
>
> Hi fromA Toulouse (France),
> I noticed for quite some time that there is often a significant
fuel
> smell in the garage after having driven my Pantera. After some
recent
> investigation I found that the underside of the car was
partially wet
> from fuel that was releasedA from the fuel tank venting hose.
That does
> not look normal, right? Does the fuel tank venting have some
device
> installed that prevents liquid fuel leaving the tank?
> Cheers
> Hartwig
>
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References
1. mailto:mikeldrew at aol.com
2. http://www.Panteraclubnorcal.com/
3. mailto:hartwig.asshauer at airbus.com
4. mailto:mikeldrew at aol.com
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