General Question, How Do You Know When Your Tank Is Full???

[Maxxxykins]

Hi All,

Might sound like a stupid question but whenever im running near empty and I go to fill up, I usually put 40-45 quid in but never want to go any higher, I haven't yet got a completely full tank, maybe a line off of it.

Begs the question (hit me if im an idiot but this is my first car :') ) does it just stop when it gets full or will it literally pour out of my car and go all over me?

Can't believe im asking this.. <_<

Cheers.

[spursalex]

The pump nozzle will click and stop automatically- you'll feel it!! Never let it click more than twice!

Not a silly question at all.

[spursalex]

To explain better - fill away, when your tank is nearly full the nozzle with click in your hand and automatically stop fuel from flowing. You can either stop here or continue to pump until it clicks a second time. You are then full! If you are interested in saving a tiny bit more money, only half fill your tank each time- this means you are carrying less fuel, meaning less weight, meaning better economy. Although the savings are probably very, very small!!

[neau]

I've heard that the opposite of this i true? that if your tank isnt full the fuel sloshes around and creates more fumes that escape? this sounds like a lot of bs as im typing this though. ha

[spursalex]

I doubt it! It is the vapour given off by petrol, then mixed with air that is flammable- not the liquid itself (this is the underlying principle of internal combustion). If you smell petrol you are smelling the vapour. If this is the case get the hell out of your car!! Vapour will not escape from your fuel tank unless it is damaged.

Alex

[Stoney871]

Usually you can tell when the tank's getting full as you hear a whooshing noise as the fuel comes up the filler pipe just before the nozzle clicks.

The pump nozzle has a device in it to detect back pressure that stops the fuel flowing.

[DanGersFord]

The pump stops automatically I usually pull the nozzle out a wee bit once its clicked and top it up a bit more it usually clicks again but keep an eye on it if you've pulled it out abit more

[FOCA]

I've heard that the opposite of this i true? that if your tank isnt full the fuel sloshes around and creates more fumes that escape? this sounds like a lot of bs as im typing this though. ha

The pertol tank on a modern petrol-engined car has an activated charcoal cannister that prevents perol vapor escaping from the tank, but allowing it to "breath" (to prevent a vaccum or pressure build- up) or there is a sealed expansion tank or the tank is of a special design - so petrol vapors cannot escape in any event

A full tank of fuel represents a significant amount of weight and only filling your tank halfway will save fuel in the long run so if you only fill up (a full tank) once a month if you fill up 1/2 a tank it will save a little fuel because the car is lighter, it may be a small improvement, but over the course of a year the small savings will build up,

A Mondeo mk3 has a 58.5 litre tank, 1 litre of diesel weighs 0.84kgs - 58.5 x 0.84 = 49.14 or approx 50 kgs, 1/2 of that is 25kgs - a significant weight and noticable in acceleration, braking and in MPG, (and traction!)

Petrol is lighter (0.75kgs per litre, off the top of my head), and Focuses and Fiestas have smaller fuel tanks, but the cars are lighter too (so the lighter weight of half a tank of fuel has a more significant effect)

If you do very long runs or are on a long trip, touring, or live in a remote location, etc probably best to fill the car right up

Just a question of balance i fill up to 1/2 a tank then when i refill it when it gets to a 1/4 - unless im going on a long run - then i just fill it right up My ex briims her tank every month and my dad runs his car permanently on fumes/ in the red, my ex is carrying extra weight she does not need to (in the fuel tank!) and my dad often has to waste time/ fuel looking for petrol stations etc

[Stoney871]

I find my car feels better on the road with a full tank, more planted.

My old Mk1 used to feel really different to drive when the tank was nearly empty.

[yorkiewhite]

Hi All,

Might sound like a stupid question but whenever im running near empty and I go to fill up, I usually put 40-45 quid in but never want to go any higher, I haven't yet got a completely full tank, maybe a line off of it.

Begs the question (hit me if im an idiot but this is my first car :') ) does it just stop when it gets full or will it literally pour out of my car and go all over me?

Can't believe im asking this.. <_<

Cheers.

I was told by the Audi techs that the proper way to fill it full is to fill it until it clicks off once then count 10 secs then fill again until the second click, that way they assured me i would have a full tank. It worked for me everytime, and by doing it the same way each time you can work out your calculations for MPG.

[iNath]

I was told by the Audi techs that the proper way to fill it full is to fill it until it clicks off once then count 10 secs then fill again until the second click, that way they assured me i would have a full tank. It worked for me everytime, and by doing it the same way each time you can work out your calculations for MPG.

That's my method :)

[Philf1]

TBH does it make that much difference? I just fill till the first click and call it a day. Don't drive around on fumes either,my kids used to do this all the time, lost count of how many times I had to rescue them with a can atmy expense! Oh that's why they did it.!!

Also don't fall for all that driving miles to save 1p a litre nonsense. You probably waste more than you save , by all means go for the cheapest if it is en-route anyway however.

[jimrex]

I am a stickler for getting a round figure, so if it clicks to £65.04, I have to round it to £66, regardless of the number of clicks!

I do notice a remarkable difference with a full tank, as Stoney said the car feels more planted. My dad has a rear wheel drive car, and he always had a full tank when we had snow to get weight over the back wheels!

I have once had petrol pour out when I had my first car, faulty pump maybe... not much but enough to make the rest of my journey smell fantastic :P

[Stoney871]

My missus gets me all the time- why don't you to to Asda and save 3p per litre???

My Asda is 10 Miles away, the trip there and back swallows up any gain straight away.

Missus doesn't quite get it though.

[Maxxxykins]

Thanks for the advice guys!

And I certainly feel a difference when I fill up my car, it seems like it just...goes faster or runs better (not that it runs bad anyway) when its been filled up, as odd as it sounds.

[b1g_dav3]

Thanks for the advice guys!

And I certainly feel a difference when I fill up my car, it seems like it just...goes faster or runs better (not that it runs bad anyway) when its been filled up, as odd as it sounds.

Probably your car being happy that you've spent money on it, it tends to work with women too, only the car is cheaper.

[DanGersFord]

Probably your car being happy that you've spent money on it, it tends to work with women too, only the car is cheaper.

Lmao

[FOCA]

Thanks for the advice guys!

And I certainly feel a difference when I fill up my car, it seems like it just...goes faster or runs better (not that it runs bad anyway) when its been filled up, as odd as it sounds.

There may be actual technical reasons for this, firstly, the ECU may go into a "fuel saving" (read low power) mode when the low fuel warning light goes on

Secondly, i higher fuel level may help the supply of fuel (better pressure/ fuel head/ fuel surge less liable etc)

Or it may just be a placibo effect

When i have a full tank, i can feel the extra weight slowing the car down, If you consider a full tank of fuel (Mondeo) weighs almost 50kgs (approx 8 stone- the weight of a supermodel) its not surprising

I watched the BTCC saloon car racing and i remember the chap talking about how much an extra 18kgs was going to slow his race car down, ("success" ballast is added to BTCC cars to slow them bown, upto 45kgs, i think)

I know our cars are not race cars but the same principals apply / weight saving is also a cornerstone of hypermiling (economy modifications and techniques)

[Stoney871]

I really did notice the difference in my Mk1.

I could tell without looking at the fuel gauge that the tank was low as the back end felt very loose.

The car idle the road far better with a full tank.

(something akin to the old Capri handling pack- a concrete slab in the spare tyre well)

[Mordey]

(something akin to the old Capri handling pack- a concrete slab in the spare tyre well)

Showing your age now Stoney

[Stoney871]

Cheeky, I'm only 43 tomorrow.

(drat, did I admit that?)

[FOCA]

Happy birthday!

They used to put bags of cement in the boot of mk2 jags (the ones that were not rolled on the Sweeny)

[Stoney871]

Happy birthday!

Ta, feel old now.