[DeTomaso] Fuel tank ventilation - fuel spill
Mike Drew
mikeldrew at aol.com
Sun Mar 6 16:28:43 EST 2022
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 www.Panteraclubnorcal.com
Let me know what you find out!
Mike
Sent from my iPad
> On Mar 6, 2022, at 13:13, HARTWIG ASSHAUER <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 <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 <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
>> >
>> > The information in this e-mail is confidential. The contents may not be
>> > disclosed or used by anyone other than the addressee. Access to this
>> > e-mail by anyone else is unauthorised.
>> > If you are not the intended recipient, please notify Airbus immediately
>> > and delete this e-mail.
>> > Airbus cannot accept any responsibility for the accuracy or
>> > completeness of this e-mail as it has been sent over public networks.
>> > If you have any concerns over the content of this message or its
>> > Accuracy or Integrity, please contact Airbus immediately.
>> > All outgoing e-mails from Airbus are checked using regularly updated
>> > virus scanning software but you should take whatever measures you deem
>> > to be appropriate to ensure that this message and any attachments are
>> > virus free.
>> > _______________________________________________
>> >
>> >
>> > Detomaso Email List is not managed by POCA
>> > Posted emails must not exceed 1.5 Megabytes
>> > DeTomaso mailing list
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>>
> The information in this e-mail is confidential. The contents may not be disclosed or used by anyone other than the addressee. Access to this e-mail by anyone else is unauthorised.
> If you are not the intended recipient, please notify Airbus immediately and delete this e-mail.
> Airbus cannot accept any responsibility for the accuracy or completeness of this e-mail as it has been sent over public networks. If you have any concerns over the content of this message or its Accuracy or Integrity, please contact Airbus immediately.
> All outgoing e-mails from Airbus are checked using regularly updated virus scanning software but you should take whatever measures you deem to be appropriate to ensure that this message and any attachments are virus free.
-------------- next part --------------
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 www.Panteraclubnorcal.com
Let me know what you find out!
Mike
Sent from my iPad
On Mar 6, 2022, at 13:13, HARTWIG ASSHAUER
<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 <[1]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
<[2]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
>
> The information in this e-mail is confidential. The contents may
not be
> disclosed or used by anyone other than the addressee. Access to
this
> e-mail by anyone else is unauthorised.
> If you are not the intended recipient, please notify Airbus
immediately
> and delete this e-mail.
> Airbus cannot accept any responsibility for the accuracy or
> completeness of this e-mail as it has been sent over public
networks.
> If you have any concerns over the content of this message or its
> Accuracy or Integrity, please contact Airbus immediately.
> All outgoing e-mails from Airbus are checked using regularly
updated
> virus scanning software but you should take whatever measures
you deem
> to be appropriate to ensure that this message and any
attachments are
> virus free.
> _______________________________________________
>
>
> Detomaso Email List is not managed by POCA
> Posted emails must not exceed 1.5 Megabytes
> DeTomaso mailing list
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>
> To manage your subscription (change email address, unsubscribe,
etc.) use the links above.
>
> Members who post to this list grant license to the list to forward
any message posted here to all past, current, or future members of
the list. They also grant the list owner permission to maintain an
archive or approve the archiving of list messages.
The information in this e-mail is confidential. The contents may not be
disclosed or used by anyone other than the addressee. Access to this
e-mail by anyone else is unauthorised.
If you are not the intended recipient, please notify Airbus immediately
and delete this e-mail.
Airbus cannot accept any responsibility for the accuracy or
completeness of this e-mail as it has been sent over public networks.
If you have any concerns over the content of this message or its
Accuracy or Integrity, please contact Airbus immediately.
All outgoing e-mails from Airbus are checked using regularly updated
virus scanning software but you should take whatever measures you deem
to be appropriate to ensure that this message and any attachments are
virus free.
References
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