Gas tank pressure

[Rocky]

You guys know when you run almost empty and you go fill the tanks...when you turn to take out th egas cap, you can hear pressure release right? My car stopped doing that..possible air leak somewhere in the fuel lines?

[SLAMMED_C]

ummm.. no. if you had a leak in your fuel evaporative/purge system... you'd know about it.. with a big check engine light on in your cluster! I dont think that you will have that vacuum noise all the time.. especially if your tank is empty or really low on fuel.. you have to remember that, that is a lot of volume to pressurize and with an empty tank it may not happen.

[tinter101]

I've noticed that that hiss is more evident in warmer weather.
Does that make sense to the timing that you started to not
hear it?

[jnolte]

my c36 had the "hiss" when u opemed the tank.

The 43 dosent do it as much....not as often.

But if u did have a fuel leak, you would get a CEL light from your OBD doing its job

[SLAMMED_C]

I've noticed that that hiss is more evident in warmer weather.
This will be true, the warmer weather will increase temps inside the gas tank.

[J Irwan]

I have mentioned this before previousliy on Benzsport.com (when we still have that :) )

Just an FYI, I thought I'd share again with you all..

Please avoid filling up the gas tank below 1/4 mark...

I usually fill up the gas before the light is lit... (I fill it up everytime it hit 1/4 mark).

I have learned my lesson from Owning my E36 3 series..

These E36 3 series and our W202 (actually many mercedes model) have the fuel pump inside the fuel tank.
And it actually utilize the liquid-fuel as part of the cooling system.

What happend if you always fill up when the needel already below the "E", your fuel pump/regulator will failed prematurely..
(It'll be even worse if you have a habit of driving the car hard with almost no fuel (below "1/4" on the tank ;) )

IT's not a fun sympton, as one time you're able to start the car just fine, and some other time the car keep crancking....and...crancking but won't turn over.. (crancking pretty strong, so you could exclude, battery and starter problem)..


Also I never heard the "hiss" when I open the gas cap...
probably because I always fills up at "1/4" mark :)


Regardz,

[Rocky]

I always fill up at the 1/4 mark.