A little confused on the gas economy and gas tank specs...

Jettamatic · Mar 18, 2008

So supposedly the gas tank has 55L worth of fuel and included in this is 7L of reserve (im guessing this is when the light turns on?) 1st Q: Is this 55L VENTED OR UNVENTED? How much extra would you say can fit if vented if not 55L. Secondly, I asked the question about the fuel light because I think my fuel guage may be crazily off. Im not sure if its diff in the Mk4's but my friends Mk3s are pretty much done the moment the arrow hits the E. My car typically has like 5L worth of fuel even when the guage is totally empty, and close to 12L the moment the light turns on (based on me tanking up all the way to the top without venting and doing 55L- w.e. amount I put in). HOWEVER, i tried once driving only 100km (again all figures are with unvented tanks) and seeing how much filled up. It seems im getting 7.5L/100 km?? The light turns on at about 680km and my car today made it today to 740km when hitting E. 5L still supposedly remained in the tank. Do the figures for the car sound normal?(All city driving)

Joe_Meehan · Mar 19, 2008

I assume you mean diesel not gas?

I believe you are on the right track, but since different models have different venting, those numbers vary and I frankly I don't even know how much difference I get in my NB. I think it is about a gallon/4L but I am not sure. I really have not worried about it.

McBrew · Mar 19, 2008

VW does not list the vented number. Vented, I have put nearly 17 gallons (~62.5 L) in my tank.

Jettamatic · Mar 19, 2008

Fair enough. Whats still bothering me though is why my light comes on so prematurely (like I said I can fuel up far in advance of the 7L reserve) When the light comes on I defintely do not have 7L more like 12L and when its totally on E I have like 4 or 5L or so but the consumption of the car seems quite a bit higher then it should be so it doesnt make any sense.

nicklockard · Mar 19, 2008

Your fuel tank sender unit may be misaligned. To check, lift the rear seat up, lift up the carpet flap and unscrew the fuel tank lid (3 phillips head screws.) Check to see that the arrow on the white portion of the fuel sender unit is aligned with the notch or arrow on the metal next to it. If not, then use a screwdriver to tap on the plastic lid tongs gently, moving around in a circle with patience until the lid is finally loose. Rotate assembly to align and retighten lid and reverse process.

The fuel sender unit's accuracy depends on being aligned properly.

wjdell · Mar 19, 2008

12 L or about 3 gals on a 14.5 gallon tank. PD's have lift pumps I think, the higher the level the easier to lift. The better the heat is dispersed from the pump. The fuel tank is also acts as cooling tank when hot fuel from the engine is returned. What month and year was this car built, maybe VW wants that light to come on at 3 gals or 12L.I have never seen my fuel light, not even sure if it works. I have seen my snowflake in cluster twice now at 39F. My only car accident was black ice, I thought the road was wet. If I had only had that snowflake.

Jettamatic · Mar 19, 2008

No my car isnt PD, as far as I know it was built in '99 but its a 2000 model.

MikeMars · Mar 20, 2008

My old car had the reserve wildly off (less than 2 litres left when the light came on, it would cut out if on a steep slope with the light). I asked my garage (supposedly a 'german car specialist', i.e., VAG, BMW + Merc) if it could be adjusted and they didn't know how. So the above information would have been very useful

The snowflake comes on too early, at 4c (4 above freezing point). It's been on more often than not in the last 5 months, and I have not yet encountered an icy road.

Lug_Nut · Mar 20, 2008

Maybe your temperature indicator is sensing the air temperature and not the pavement temperature? Pop the sensor out of the front bumper and let it drag on the road surface. Then the more accurate reading can be calibrated to 0C pavement rather than worring about liquid precipitation falling on sub-freezing pavement and icing.

Warmer than 4C and the cold rain will likely remain liquid and run off the road. Colder than 0C and the snow falling remains snow on the pavement. It's that just above freezing air and just below freezing surface that creates most of the ice. +4C is a logical threshold for a caution indication.

n1das · Mar 20, 2008

My TDI doesn't have a GAS tank!

Rated tank capacity is 14.5 US gallons. The low fuel light is supposed to come on when there's 1.9 gallons left in the tank.

The 14.5 gallon rating assumes no venting of the extra space allowed for expansion of gasoline vapors in the gassers. I think the gasoline capacity rating assumes space is allowed for expansion of vapors. I think the 14.5 gallon rating was simply carried over from the gassers since we're using the exact same tank, minus the vapor recovery system that the gassers have.

Since expansion of diesel is a non-issue, you can safely top it off all the way to liquid at the top of the filler neck, giving you just under 17 gallons of total capacity.

From previous threads on the subject, some people have experimented and learned exactly how much you can squeeze into a tank by running the car out of fuel on purpose, partially filling it with a precisely known amount of fuel, and then driving a short distance (under 5 miles) to the nearest gas station and filling it with DIESEL and topping it off with liquid at the top of the filler neck. I've heard of 17 gallons but people who've experiemented generally came up with 16.7 or 16.8 gallons to fill it from completely dry to liquid at the top of the filler neck. The most I've ever squeezed into my 02 Golf TDI is 16.3 gallons. I didn't dare go any farther because it wasn't worth the risk of running out of fuel. I'm inclined to think around 16.5 gallons is what the tank actally holds, not counting the amount of fuel standing in the filler neck and plumbing down to the tank.

14.5 gallons rated capacity, assuming no venting.
16.8 gallons from bone dry to liquid at the top of the filler neck.
1.9 gallons left in the tank when the low fuel light comes on.

AudiLikeA4 · Mar 20, 2008

n1das said:
My TDI doesn't have a GAS tank!

Rated tank capacity is 14.5 US gallons. The low fuel light is supposed to come on when there's 1.9 gallons left in the tank.

The 14.5 gallon rating assumes no venting of the extra space allowed for expansion of gasoline vapors in the gassers. I think the gasoline capacity rating assumes space is allowed for expansion of vapors. I think the 14.5 gallon rating was simply carried over from the gassers since we're using the exact same tank, minus the vapor recovery system that the gassers have.

Since expansion of diesel is a non-issue, you can safely top it off all the way to liquid at the top of the filler neck, giving you just under 17 gallons of total capacity.

From previous threads on the subject, some people have experimented and learned exactly how much you can squeeze into a tank by running the car out of fuel on purpose, partially filling it with a precisely known amount of fuel, and then driving a short distance (under 5 miles) to the nearest gas station and filling it with DIESEL and topping it off with liquid at the top of the filler neck. I've heard of 17 gallons but people who've experiemented generally came up with 16.7 or 16.8 gallons to fill it from completely dry to liquid at the top of the filler neck. The most I've ever squeezed into my 02 Golf TDI is 16.3 gallons. I didn't dare go any farther because it wasn't worth the risk of running out of fuel. I'm inclined to think around 16.5 gallons is what the tank actally holds, not counting the amount of fuel standing in the filler neck and plumbing down to the tank.

14.5 gallons rated capacity, assuming no venting.
16.8 gallons from bone dry to liquid at the top of the filler neck.
1.9 gallons left in the tank when the low fuel light comes on.

17.3 gallons BONE DRY. I've run out of fuel and that was the refill amount. I recently did it againand filled at 17.129, but I died on a hill, so I believe the sloshing was the culprit. Not running the tank that dry anymore, once the fuel light comes on I fill asap.

DanG144 · Mar 20, 2008

2005 BEW Jetta (so with lift pump), takes 16.5 gallons (62.5 liters) to refill to the top of the neck on my tank with vent removed, after running completely dry on level pavement.
With no adapatation the low fuel alarm was coming on at 14 gallons(53 liters) used. I adapted it with VAG-COM so that it alarms at 14.5 gallons (55 liters) used.
DanG

n1das · Mar 21, 2008

AudiLikeA4 said:
17.3 gallons BONE DRY. I've run out of fuel and that was the refill amount. I recently did it againand filled at 17.129, but I died on a hill, so I believe the sloshing was the culprit. Not running the tank that dry anymore, once the fuel light comes on I fill asap.

Does the 17.3 number include filling the fuel filter with fuel?

AudiLikeA4 · Mar 21, 2008

n1das said:
Does the 17.3 number include filling the fuel filter with fuel?

Maybe, I have an in-tank fuel pump, but I think it shuts off when no fuel is going thru it.

This was in a 2004 BEW, I've filled quite a few times at 16.9-17.1 gal, depends on how determined to FILL the tank you are.

VFchicago88 · Mar 22, 2008

my 04 golf will take 17.5 gallons to the brim.

A little confused on the gas economy and gas tank specs...

Jettamatic

Member

Joe_Meehan

Top Post Dawg

McBrew

Top Post Dawg

Jettamatic

Member

nicklockard

Torque Dorque

wjdell

Top Post Dawg

Jettamatic

Member

MikeMars

Veteran Member

Lug_Nut

TDIClub Enthusiast, Pre-Forum Veteran Member

n1das

TDIClub Enthusiast, Veteran Member

AudiLikeA4

Veteran Member

DanG144

Top Post Dawg

n1das

TDIClub Enthusiast, Veteran Member

AudiLikeA4

Veteran Member

VFchicago88

Banned