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Chris VW Master Tech
Chris VW Master Tech, VW Technician
Category: VW
Satisfied Customers: 327
Experience:  City & Guilds 1,2,3 Vw Master Tech cars&vans, VW Licence Tech
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Golf Gti: Mk4..a Fuel Leak from the filler cap..Fuel tank

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My Mk4 Golf Gti 180bhp has a Fuel Leak from the filler cap. The Fuel tank appears to be pressurising itself to the point that it forces fuel out the Filler cap. Have you any ideas what may be causing the issue? I have tried changing the two valves in the filler neck, checking that there are no blockages in the Charcoal canister and the venting fuel lines, but it's still pressurising, any ideas thanks
Hi sorry to here about your problem, the 1st thing you need to check , has any work been carried out on the car recently, and then this problem has started since then, if so was it anything to do with the fuel system, i suspect that one of the fuel lines is round the wrong way , by this i mean the fuel feed is connected to the return line, this can happen when the fuel filter is replaced or if someone has dropped the tank or touched the fuel rail and injectors in anyway, the car can still run ok, and i have seen it many times, you need to check this 1st , hope this helps Chris
Customer: replied 7 years ago.
Thanks for your response Chris, we have just bought the car so not aware of any work being carried out on the Fuel system. What is the most likely area for mixing up the fuel lines?. As far a I can see the fuel filter is straight forward when replacing, as there is only one pipe IN and one pipe OUT and connections are all shaped, so don't think these can be mixed up with the return line. The only area can think there could be a mix up is where the fuel lines enter the engine bay at the driver side strut, there are 3 connections there. I haven't looked at any fuel tank connections

Hi the area by the suspension strut next to the coolant bottle is where they can get mixed up, usually the black fuel connector is the feed the blue connector is the return and the white connector is for the charcoal canister and purge valve you need to check these 1st .

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