Technical Petrol leaking when full, but from where?

[Fabius]

Our 2013 Panda 4x4 TwinAir leaks fuel onto the ground under the car if we fill it right up. And we can smell petrol for some time until we've run the petrol level down. Not sure at what point the smell disappears.

Our mechanic said he can't see an obvious place for the leak. All he can suggest is to try a new fuel filler neck pipe, because that's the most likely location. But they cost about £300 from Fiat.

I have no better ideas – other than never filling fully up again! Anyone had this problem? Does this sound like the solution? I don't mind paying if it'll fix the problem but it's an expensive gamble.

 

[The Panda Nut]

Firstly you must not fill the car to the brim. When the first cutoff occurs when filling, STOP. In the wheel arch is the evapouration cannister and its designed to collect and trap vapour m the tank escaping to athmosphere, and cycle this into the engine to prevent pollution. If you over fill the tank it can fill up, and its not designed to hold fuel. There are pipes from the tankto the engine attached to it. If you over fill the tank there is also a drain from the filler neck. Over filling will wreck the evap cannister and I can tell you they are expensive, and it may affect other things there is a solenoid valve in the system and thats eye wateringly expensive too. You should get the o/s rear wheel arch liner out and find out asap to avoiad the problem escallating and also the risk of fire.

 

[jrkitching]

we fill it right up

What exactly do you mean by fill it right up?

As the previous poster had said, the maximum you should ever fill the car to is the point where an automatic fuel pump cuts off with the nozzle inserted fully. This should leave an air space of about 5-7 litres in the fuel system.

Without this air space, the fuel system won't work properly and you risk damaging some expensive parts.

You must never try to dribble in more fuel after the pump cuts off.

There is a clear and specific warning to this effect in the vehicle handbook. My own view is that Fiat should also have put a warning label on the fuel cap.

All he can suggest is to try a new fuel filler neck pipe

If you follow the manufacturer's instructions when refuelling, there should never be any petrol standing in the filler neck pipe.

 

[Fabius]

Sorry for the ambiguity. When I said fill it up, I meant until when the pump cuts out. To me, that is "full".

 

[jrkitching]

Thanks for the clarification.

The first thing I'd do is to fill it as you normally would at a garage as close to home as possible, then crawl under it and look carefully for any leaks.

A possible next step would be to put a tracer dye into the fuel tank, fill it up and then repeat the crawl with a UV torch.

Something like this.

 

[Herts Hillhopper]

This link to the Forum's version of ePER (the Fiat parts catalogue) should open to show the various pipes connecting the fuel filler to the tank and may help you explore where its leaking from... https://eper.fiatforum.com/en/Drawings/Detail/F/F/GIN/33/102/0/20/1/SubGroup . On my Mac I can right-click on the drawing to open a bigger clearer version in a new window (which can be found here https://data-84-eper.fiatforum.com/26/2617B126408330868779EC702AD2271F.png)