Tank rust or just the filler neck

[EDDIE-F]

My car is sucking rust out of the tank, it has for years and I filter it out . My question is does the rust form in the filler neck or does the tank itself rust?
I am reluctant to change the tank as it looks like a nightmare to do.

[Village Idiots]

I never had rust in fuel problems with my Scala (that I was aware of!) I changed the filler neck as it looked really crusty and thought it wouldn't be long before rust problems. I changed the tank when it started leaking fuel: corrosion of the top right hand corner seam (apparently a common area). Not the easiest of jobs.

[chopperoli]

What year is your car? The necks are definitely a known weakness. They do rust. But so can the tank especially now E5 and E10 fuel arrived. Have you fitted an additional filter before the pump?

[mark1gls]

Is your car stored away over the winter or in regular use?

If the car is left over the winter months it’s best to fill the fuel tank as it reduces the condensation in the tank.

[mark1gls]

If you shine a torch down the fuel filler neck from the filler cap end, you should be able to see if there’s a problem with it as they rust away at the top as that’s where all mud sits on them.

[RussGLAuto]

Right then Eddie,

I feel your pain. I first noticed fuel issues right after my refurbished & perfect running Pierburg Carb was re-fitted in place of one of those awful webber conversions. After a week or two's driving (stirring up all the muck in the tank) started coughing and spluttering, no power, you get the picture...

I checked the clear fuel filter in the engine bay - uh oh, a hefty amount of small rust particles. Evidently the filter had let through some small particles, blocked the jets, resulting in one sick puppy.

The car had it's fuel neck replaced with some exhaust tubing (!) at some stage in it's life as noted on a previous MOT cert - thats where the rust seems to take hold. Dreadnaught customs sorted me out with a new stainless one.

I didn't check the tank, my second error, perhaps this was contaminated from fuel neck rust, who knows. I could have removed the fuel sender and checked from their. Be careful, they are delicate and rare.

Eventually got a new tank from VW Heritage just in case and a new set of hard fuel feed and return lines from a Golf Mk1:

https://www.classic-vw.co.uk

As I don't have a garage lift a local classic garage changed both out for me in a day and cleaned out the carb jets. You are correct in thinking it's not easy, the rear suspension beam has to be unbolted (4 x bolts) and dropped down to get the tank out.

However, it is possible to DIY.

There is a chap in 'Merica who is doing quite a good series on recommissioning jobs on his Scirocco GTi, one of which is, you guessed it, fuel tank removal and replacement if you wanted to have a stab yourself. I know my limits and yes, it did cost me ££££. Here are the links:

https://www.youtube.com/watch?v=lvyjW5uM1BM

https://www.youtube.com/watch?v=eHKi7V5C-30

Worth noting the fuel delivery system on the GTi is far more complex than on the simple carb versions such as mine. You don't say which you have.

What have I learned? Well, interestingly, on inspecting the old tank and fuel lines, it was the fuel lines that were badly corroded, like furred arteries they were with rust. They looked fine externally. As did the tank. There was some sediment in the tank, but overall, not too bad.

Best part is, she now starts first time every time. I know it seems daunting, but I recommend checking everything right from the filler cap to the engine to ensure you're not leaving the problem to remain where you least expect it, like I did.

Oh yes, replace all the rubber lines while your at it.

Good luck!

[essextom]

rust generally forms in the neck, but the tanks are old now, i have seen the sender unit break down and cause debris also.
id remove the small round inspection panel under the rear seat, remove the sender unit and have a good look inside.

I can supply stainless fuel necks if needed.