Hello,
Every since i purchased my 951 last year, everytime i fill up the gas tank it over flows. I used to be getting fuel smells in the cabin, but after tightening the hoses at the fuel level sending unit, it decreased a lot. It's still there but only lasts a few seconds.

The problem is, the gentleman at the fuel station informed me that sometimes the tank is under pressure, thus petrol spills out when it get's full. Even when he removed the fuel nozzle and before tightening the fuel tank cap, i could see fuel bulging out from time to time untill i start the car.....he also infored me that is normal....

Is it normal for EVER time you fill up you get this? should i be concerned?

TIA

 

I don't know about everybody else, but every time I fill my 944's, the auto-shutoff on the nozzle always causes it to spill over, so I've just stopped using it. I just fill until I hear it get to the top, and a little bit splashes out, then I stop.

 

Even with the auto nozzle thing off. If i fill it up and before i close the cap, i see petrol gushing and stoping, then gushing and stopping etc....goes on untill i close the cap and start the car......

 

Mine always auto shuts off early. Itll stop, then I can usally cram 2 or 3 liters more in. Also it only takes 60 or 65 usually, even when im into reserve.

 

65-65 on reserve? mind takes in almost 80 if the light comes on (which only happened once)

I fill up when there is 1/4 left in, that takes anything between 55-60.......

 

I almost always put 72 litres in. I drive until the light comes on, then another 50-60K.
Fuel gushing out does not sound right at all.
I would fill it by ear. Once you hear it bubbling up the fill tube, quit

 

never ever had an overflowing problem. Always shuts off well before I can see the fuel level through the filler hole.

 

for me it usually shuts off a long while before the tank is full...

 

Me too. On the cabrios this happens even more unless you fit the nozzle upside down in the fuel tank opening.

Hussam, it's not normal for your tank to overflow. Either the pumps are not stopping correctly, or there's something unusual in your filler tube.

Where does the overflow spill? Outside the car on your rear fender, or is it sucked in by the overflow hose? If so, does it leak underneath the car at all when it overflows?

 

Luis: Maybe my explanation was quite accurate.

When filling, everything is fine. Once it gets almost full, petrol splashes out (small amount). The gentleman at the gas station then slowly takes out the nozzle and slowly fills the tank, and keeps doing that untill it's "FULL". It doesn't overflow, there is also a groumet (sp?) on the rear fender near the tank cap to catch and drain any spilled petrol, which works fine. But this happens EVERY time i fill up.........that's what worries me.....

 

I always thought the early shut-off was because the fuel was foaming up and it touched the nozzle, making it shut off. After a few seconds it settles down and there's room for more again. ? No clue about the overflowing... is there a breather for the gas tank somewhere? That might be clogged or stuck shut? I don't know but I remember hearing something about something like that.

 

There is a small vapour outlet at the top of the tank (your drivers side) If you have PET you can see it, not that it is clear to see or any info about it. This is to allow the tank to breathe.
I had filled my tank to the brim the evening before we were to go away early in the morning for a weekend. When I went to the car I could smell petrol and could see a damp patch round the rear wheel. At this point not knowing what it was causing this (thinking bust tank) and the petrol dripping onto the exhaust heat sheild, ended up hiring a car instead.
Basically overfilling and parked on the road with the camber tilting the petrol that direction also did not help.
To avoid spillage etc. don't overfill. You can always go back and get more!

 

One possibility is expansion of the gasoline. I don't know off hand how much the volume will change but I do know it will. My guess is you are filling up from an underground tank and the fuel is cool. Maybe 55 or 60 F. Then up into your above ground oven in the UAE. The fuel heats up, expands and you get the runoff.

Ok, one minute quick search on Google. I knew I wasn't dreaming this up.



Yours is an example of linear thermal expansion.
The volumetric expansion coefficient [dV/V)/dT] is generally taken as 3 times the linear coefficient [(dL/L)/dT]. So, if a 75L steel tank full of gasoline at the same temperature, are both heated by 20 K (36oF), gasoline would spill out.

The linear coefficient of thermal expansion for steel: 12x10-6/K
The volumetric expansion for gasoline: 95x10-5/K

Excess volume of gasoline after heating:

(75)(20)(95x10-5 - 3x12x10-6)= 1.37L = 0.36 gallons

Therefore, it is recommended never to fill a car gas tank to the very top.

 

Litres? PETROL?? OMG!!!! What the hell is going on?!?

 

you said that you have tightened hoses - the ones on the top of the level sender? thats a good place to check. i'd suggest two things: the next time you fill up, when you get home, pull the carpet back there and see if there is any raw, wet fuel around the sending unit. the black plastic cap ring is threaded and may just need to be tightened down.

i've also seen (on my past 86 951) that the top of the sending unit can crack (one of the two metal hose fittings) and (this is the big one) the base of the fuel neck can crack where it joins the tank. these tanks are plastic (or something like it) and for some reason, can crack around those joints.

i fixed the fuel filler neck by using a fiberglass repair kit and glopping on the epoxy pretty thick. sealed up perfectly.

i fixed the cracked tube that exits the level sender by using JB Weld. again - glop it on thick and let it cure thoroughly. worked like a champ.

but...the first step is to fill up, and then pull the carpet and check for raw fuel puddled back there. (but don't forget to let the level go down before you start to pull the sending unit...that can get smelly and messy)

good luck!