Drove up to Scotland on Monday (~350 miles) and already had 60 miles out of a full tank. Not far from my destination I had clocked 405 miles and the tank range had been on 0 miles for a short while (Average showing 44mpg for 200 motorway miles and the remainder A roads). I stopped at a small local petrol station and put a tenner in, 8.2L, to be on the safe side and to get me to my destination, another ~ten miles then filled up with 48L. The following day I covered about 230 miles of A roads at 44mpg and refilled with 24L which adds up to the trip computer being spot on, but, the fuel gauge didn't drop for the first 100+ miles. I initially thought the sender must have gone but on rethinking it, I wondered how I managed to fit 55L in my tank. I checked the book which states the capacity at approximately 45L which backs up my previous fill ups. I wondered if the petrol station was delivering short measures but the following day's figures and the behaviour of the gauge proved otherwise. Has anybody else managed to overfill by 10+L?

Covered 1100 miles in total this week and the car behaved impeccably. Very pleased with my purchase :yes:

Update: Found a similar thread: 50L fuel tank from November last year. It talks of an expansion tank that I may have unwittingly filled :|

Edited 26 August, 201015 yr by Fatbloke

Update: Found a similar thread: 50L fuel tank from November last year. It talks of an expansion tank that I may have unwittingly filled :|

Hi Fatbloke.

We drove our Fabia 1.9TDI (57) back from Spain via the Santander to Plymouth ferry about five weeks ago. About 50 miles before Santander we stopped at a small country filling station and asked the young lad to fill the tank. It took him a long time and we were on fumes when we stopped, he managed to get over 52 litres in the tank. I couldn't believe it at the time.

We drove to the ferry and after docking at Plymouth drove all the way up through the south west and up the M5 to nearly Cheltenham before the bar guage dropped from full. At one point I was concerned that he had filled the tank to the brim and the sensor had stuck at the top of the tank.

So it does seem to prove that there is extra capacity somewhere. Interestingly enough, the young lad that filled our tank in northern Spain drove a 1952 Fabia himself. Maybe he did this regularly?

Thanks for the comment.

I've done a bit of reading around and it appears there is an expansion area of the tank that has a breather routed to the filler neck to allow expansion of the fuel in warmer weather and due to warming of the fuel as it returns to the tank from the pump circuit. The valve in the neck can be vented during filling allowing the expansion area to be filled. It is quite a common mod for the diesel burners to remove the valve internals to allow it to remain vented constantly to allow filling of the expansion area. I believe this is not recommended on the petrols as it has a greater expansion on heating. I must have inadvertently 'vented' during filling.

55-56L is about the most you can get in a mk1 tank with the ventectomy mod. I presume the mk2 tank is the same. I never managed to accidentally get more into my tank than the standard 45ish litres 'til I did the ventectomy mod though, but it is possible. (it must be!)

I had this happen on my od Mk2 1.2 petrol Fabia. Somehow squeezed in an extra 2 gallons. I thought the gauge was busted as it stayed nailed to full for over 120 miles.

I read up on the vent issue on here and now understand whats going on. If your going to be on a long run then you can actually 'lean' on the spring vent valve as you fill to top up. Wouldnt ever recommend it on a petrol unless your going on a really long run to create some space in your tank.

You probably know this but the vent gets operated by the filler cap when you screw it on. Give it a try, fill it up then push lightly on the vent with your finger, you will hear the air venting and the fuel level goes down in the neck. Its only what happens anyway when the cap goes on. I occasionaly keep the valve pressed filling my diesel Fabia if I intend to go a long way.

Safety note......dont ever do this in really warm weather or if your going to leave the car standing for any length of time. The air gap is there for a reason.

I think the design of the nozzle must have meant it operated the valve 'switch' during filling as it happened twice at the same filling station. I will be filling up at my usual station soon so will observe to make certain that the nozzle isn't interfering with the button. I suppose it is possible that the valve is stuck open, hence faulty, and the amount of fuel I get in will determine this. It is a useful thing to know about if you're about to take a long trip but as i've read and been advised it is not something to do on a petrol car as a matter of course and I'd rather not be carrying the extra weight of fuel unecessarily. Although an extra 10kg of fuel is not significant on a 1200kg car with a 100kg+ driver

Yes there is expansion space - but not 2 gallons worth.

I have a much simpler theory.

Some (privately owned) garages short change you. Their pumps don't deliver the correct amount.

I have had a lot of experiences of a privately run Shell garage filling ridiculous amount of fuel compared to my local Sainsburys.

I have checked this several times.

I complained to the local council, who got back to me and glibly said - "Oh we checked them about 2 or 3 weeks ago and it was alright" (I was under the impression they were under an obligation in law to check immediately if any complaint was made).

On the other hand the local Sainsburys have stickers on all their pumps showing when independent checks were last made and certified.

I trust my instincts

Yes there is expansion space - but not 2 gallons worth.

I have a much simpler theory.

Some (privately owned) garages short change you. Their pumps don't deliver the correct amount.

I have had a lot of experiences of a privately run Shell garage filling ridiculous amount of fuel compared to my local Sainsburys.

I have checked this several times.

I complained to the local council, who got back to me and glibly said - "Oh we checked them about 2 or 3 weeks ago and it was alright" (I was under the impression they were under an obligation in law to check immediately if any complaint was made).

On the other hand the local Sainsburys have stickers on all their pumps showing when independent checks were last made and certified.

I trust my instincts

That was my first thought and why I only did a 'get me there' top up at a small, local and expensive station, but the petrol station for the big fill was a supermarket one and the following day the gauge didn't move for over a hundred miles which is a good 2 gallons. It did the same again after refilling to return home.

Edited 28 August, 201015 yr by Fatbloke

Yes there is expansion space - but not 2 gallons worth.

I have a much simpler theory.

Some (privately owned) garages short change you. Their pumps don't deliver the correct amount.

I have had a lot of experiences of a privately run Shell garage filling ridiculous amount of fuel compared to my local Sainsburys.

I have checked this several times.

I complained to the local council, who got back to me and glibly said - "Oh we checked them about 2 or 3 weeks ago and it was alright" (I was under the impression they were under an obligation in law to check immediately if any complaint was made).

On the other hand the local Sainsburys have stickers on all their pumps showing when independent checks were last made and certified.

I trust my instincts

I dont buy that theory....

I do so many miles its not funny, at least 25000 a year. I drive the same route and know exactly what fuel my car uses and how much it costs to fill it. You cant dispute when the fill nozzle clicks off and I look at how much fuel I put in. Then I depress the vent valve and continue filling for at least 8.5 litres. We are talking volume of liquid dispensed here, not the price or pump calibration. The unused space in the fuel tank is a fact, verified by continuing to fill when its depressed followed by a sound of air being released as you fill.

The tank definately takes another 2 gallons, the number of miles I've been able to do with the mod just wouldn't be possible wihout it. The most I've done is 670 miles, which is around 55mpg. With a 45 litre tank, it would be 68mpg.

Had my 1.2tsi 6 months, 4700 on clock. Generally run it til dash shouts at me with 40/50 miles left in tank and about 350 miles travelled since last fill - ie about 1 gallon/4.5 litres left in tank; until last week all it would take to brim was 39-41 litres.. At last fill, clock showed 20 miles left - 2 to 3 litres and 364 miles travelled - was shocked to find it took 50.97 litres (even more shocked that it would mean average mpg - worked out manually- would be 32mpg even though clock showed 41) and now, having driven 110 miles, clock shows 410 miles left in tank. Interestingly, have been to local Skoda service desk with all of this and all they have suggested is to put it on their diagnotic - no mention of any expansion tank. This was the only logical conclusion I had come to , so thanks for this thread , which has reassured me; maybe I can teach the local Skoda guys something.

Separate query whilst I'm on - has anyone any real world experience of the 1.2tsi average fuel consumption. My previous vehicles' -petrol and diese-l have always returned within 5mpg of the Govt combined figures. This one's doing about 41-42mpg compared with Govt's 54mpg. My driving is 20 mile round trip to work mon-fri but not in rush hour and frequent 50mile round trips to see in-laws at weekends - all split about 50/50 on dual and single carriage A roads

Yes low 40's is what we've been getting with the current Monte TSI 86 and the Elegance TSI 85 before that. Asked the dealer to check the previous cars consumption; NFF but interestingly they managed to get a fuel computer average reading in the 60's. Never managed that ourselves and we're not lead foot drivers :wonder:

Plan to visit family in Switzerland later in the year and currently intending to drive down in the Fabia, so that should be an interesting test of the fuel consumption.

TP

Im also getting low 40 or high 30 when doing shorter runs with my 1.2 TSI

The "travel" from the tank to the cap is almost 7litres so if you keep venting you can fill that up. My mate has a gas station and we've done it many times. Also with regards to what xman is saying it is partly true, some gas stations short change you because they don't service their pumps frequently or on time. If a pump is not working at its best it can indeed "steal".

The chance of short measures in the UK is almost nil. (Not all customers are daft, those that watch these things can spot it easily & kick off soon enough)

Forecourt/pump checks are regular in the UK

& Trading Standards & HMRC come down heavy on undersales, it is theft...

You are buying a cheap product and paying lots of Duty & VAT, and anyone at it is in big trouble.

(i do see over serving on occasions and Fuel Stations are checking to be sure that does not happen

because they are having the loss and paying for fuel and duty/VAT to the HMRC and they never got the money from customers.)

If you suspect you are being 'Under served' an Empty Fuel Can in your boot means you can check your self how much the pump served.

Venting talked about here.

http://www.briskoda....l-tank-capacity

george