Over pressure in gas tank

[hru]

I have observed that my gas tank is leaking on top, at the connections for the hoses to the carburator.
When I opened the gas cap, I could then hear the air flushing out. - also the leaking stopped.

Does anybody know if this is normal ?
I have an electrical pump to the carburator.

There is a little white thing inside the engine room, just below the gas inlet - looks like a one-way valve or similar.

BR
Henrik

[krede]

When I opened the gas cap, I could then hear the air flushing out

That will NEVER happen in my car... with its rate of consumption the opposite is more likely 

[Lennart Sorth]

afik the only original tank ventilation is up near the filler cap, from where there is a little hose running down to the left side chassis  (approx under the tank).

If this has become clogged, then you could possibly have a different pressure in the tank, than in the surroundings.

Fuel will expand a bit, as it is warmed up - but as you are in Denmark, I cannot see how the fuel should expand much for the moment - maybe you are in fact experiencing the opposite: fuel-cooling => under-pressure ?

An electrical pump is obviously not original, so there can be other modifications which you should check for functionality (and probably already have?).

However, nomatter how much a pump would move the petrol around, it shouldn't be able to create overpressure ??

Under-pressure, I could understand, but not the opposite.


but then again, underpressure would not cause the leaking.

[Anders Dinsen]

Henrik, your car has the newer over pressure releif system, where the valve is fitted in the top of the fuel tank and not near the filler cap. This was changed at some point, I think in 1982 (I have a sheet documenting that in my copy of the workshop manual).

The pressure in the tank increases when you run the car because the air in the tank is heated up. Similarly, the pressure decreases again when the car is left standing to cool down. The pressure releif valve is a two way valve, that opens when a given over/under pressure is reached to compensate for both situations.

I agreee with Lennart that it sounds like your valve is clogged, but not that over pressure is not likely. In fact, over pressure is very likely to exist, particularly in cold weather where the temperature increase in the engine room is the greatest, and when the tank is near full.

The releif valve is fitted in the tank with a washer and a nut, so you need to undo these from the inside of the tank to get the valve out to check it. To do this you need to remove the float assembly with the fuel line connections.

- Anders

[hru]

afik the only original tank ventilation is up near the filler cap, from where there is a little hose running down to the left side chassis  (approx under the tank).

Yes, I think this could be root cause for the troubles. I have to look into it - I think it is pretty dangerous to have all this free gasoline in the engine room. There is also an eletrical connection to the tank which could be a potential firestarter.

My old Toyota always had under pressure in the tank. The only thing I can see making over pressure is the pump being 'untight' and adding air to thefuel circut.


A lot of murenas died of fire in the engine room - anybody knows the root causes for this ?


/ Henrik

[hru]

That will NEVER happen in my car... with its rate of consumption the opposite is more likely   
 

Anders 

Have you ever noticed that the gas pedal is a sort of multiple device - with variable positions
 - not just ON/OFF

[Anders Dinsen]

A lot of murenas died of fire in the engine room - anybody knows the root causes for this ?

Yes, that's usually the (mechanical) fuel pump leaking petrol on the exhaust manifold, but I have also heard of one example where the fire happened a few weeks after the owner replaced the petrol hoses and apparantly introduced a leak. I have a good 2 kg fire extingusher in my car now, that should be able to save what can be saved in case disaster happens.

Note that it wasn't me that commented on the fuel consumption, but Krede. Has a set of twin dellorto carburettors on his engine, and from what I understand it's breathing a very rich in the low revs. That said however, my car also consumes a lot of petrol, but that's with mostly city driving.

Here she is, by the way:

[krede]

What a nice picture... and what a glorious colour... 

Has a set of twin dellorto carburettors on his engine, and from what I understand it's breathing a very rich in the low revs

The sound that springs to the top of my mind is the one of a childs straw, in an almost empty glass 

[hru]

Note that it wasn't me that commented on the fuel consumption, but Krede

Sorry - I missed this

But the car looks real nice, the RED is real nice.........

[Anders Dinsen]

But the car looks real nice, the RED is real nice.........

Thanks a lot
There's a bit of cosmetic work that needs to be done on it, e.g. there's a good crack in the front bumper and the colours on the panels are... well different. Paint on the panel in front of the wind screen is also cracking off. All this isn't visible in the picture in this resuolution. But she's running well and tend to get people in the traffic "on their toes" so to speak - it's funny to see how traffic reacts when I'm driving the Murena.

How's your car doing otherwise, Henrik? Did you get your second one home in one piece? I notice your tag line only mentions your red one.

- Anders

[hru]

Yes, I got the second Murena home in one piece.
It's in the garage now. I am still thinking about what to do.........

- it is not very nice looking in the painting, but there are a lot of good parts in it.

What happened with the front screens - will you arrange a tour to prague ?
I still need one.

[Bagheera Lars]

Hi Anders
Nice picture of your Murena, but what´s happened to the wheels?...Last time I saw it, it was still riding its original wheels.

By the way, enough of all your red devils.... now its time for some original White Murena S, so here is a picture from my garage.

Lars Tjørnelund

[Anders Dinsen]

Nice picture of your Murena, but what´s happened to the wheels?...Last time I saw it, it was still riding its original wheels.

Well spotted, Lars!... she's running on winter tyres now, and I decided to buy a new set of Borbet rims for those. The original rims will go back on with new tyres later in the spring

By the way, enough of all your red devils.... now its time for some original White Murena S, so here is a picture from my garage.

Some annoying bug in the forum software is preventing me from making or seeing attachments, so I can't see it
BTW Lars, are you home for a coffee on the 16th? I'll be going to Espe and back with my wife (in the Grand Espace)?

[Lennart Sorth]

enough of all your red devils.... now its time for some original White Murena S

I read somewhere that white is indeed coming back ... so maybe the (few) owners of Courrege Bag's will be cheering that a bit ? :-)

Lars, you have the nicest garage of all  - with beautiful cars in it.

Currently I haven't got a garage at all - or rather I have the UK version of a garage, which is a room with a "up-and-over" door, *just* wide enough to fit a car, - but only if you are willing to sleep in the car, as the width doesn't allow anyone to get out! - unless you have a sunroof (which I have removed) :-)

- I have attached a picture of my current domicile.


This is why everybody park their car in front of the "garage", and use the garage  for storage and workshop instead. Somebody told me the reason the garage is there at all, is so you can say "yes" at the right time, when you are asked by the insurance company. sigh

(ps: I am in the process of getting my car diplomatic registered here, by which time the DK licenseplates will be history)

/Lennart

[Bagheera Lars]

The Alpine Renault Clubs annual meeting takes place at "Ellested Køretekniske anlæg" On Fyn (less than 4 km. from my home) on the 9´th of sep. 2007. More info will come out later.

Hej Anders
Ja, jeg er hjemme d. 16. I er meget velkomne til at kigge forbi. Bare giv mig et ca.-tidspunkt, så er kaffen klar.

Lars Tjørnelund