I have just posted this on the Fiat Forum but not expecting any responses soon…

Just been investigating a petrol smell from our Punto, traced to somewhere around the tank seal.

When the pump is running it almost sounds open to air, there is evidence of fuel around the tank seal. It was filled yesterday until the pump cut off, so suspected breather at first.

However, whilst the pump was running I noticed a wisp of what I assume was fuel vapour, but after I stopped the engine I looked again and noticed that the white plastic where the wiring loom plugs in has a brown stripe and has melted slightly down the length of the pin! Now this obviously has put the car out of action as fuel, fuel vapour plus an overheating plug is very bad news. I'm wondering if the overheating pin has melted a small hole in the tank cap, or more likely, the tank seal is leaking badly and fuel has got into the plug, shorting out the pins.

I don't have a drive and live on a hill with a camber, plus I suspect I shouldn't be opening the tank cap with a full tank of fuel. Anyone got an idea of what needs to be replaced/cost at an independent garage to fix?

could be the hoses and not the tank. i.e. don't go into a garage and say 'hey I think I need a new petrol tank'! (they'll do it and add on the pipe/hose/labour etc)

I know the tank itself is fine…I'm just unsure as to whether the burning pins could be just petrol making them short, or if it could be a fault with the fuel pump causing them to overheat.

Last time my wife's Punto had a leak, it was traced to the section of fuel pipe which runs inside the driver's side rear wheel arch, just below the filler cap (what an utterly mental place to put a fuel feed pipe!!).

She had run over a small piece of wood which flicked up and just nicked the pipe. It's well worth a look as it's such a vulnerable place for a pipe.

Its definitely leaking from around the tank cap/seal area, I've had the inspection hatch off under the rear seat and you can see the area around the cap is damp, with a couple of blobs of fuel sitting in screw heads.

From underneath you can also see a stain where the fuel has run off the top of the tank. The connection between fuel feed and tank cap appears dry.

If it wasn't that the tank was so full I would just open it up and have a look. Can't even drive the car now in case the overheating plug catches fire or ignites the vapour…

How effective is the anti-syphon device (if any) on the 54 reg Punto?(slight facelift Mk.2b)