Keep running out of gas w 1/4 still on the gas gauge

[gcoy]

The strange thing is that when I fill after the car runs out the tank fills up around 14/15 gallons. The tank holds 17.4.

Has anyone else had a similar issue? & yes I try to fill before I hit 1/4 but our cars go through gas so fast that sometimes I get caught off guard...

Thanks

[jeffrey146]

Really really bad for fuel pump and fuel filter to do that all the time. I would change your filter every 10k if you run it to empty over and over again.

[gcoy]

Yes, I should clarify. This is the third time in two years. Car has 104k miles & I changed the fuel filter about 3k miles ago. The fuel pump has never been changed that I know of. I bought the car w 68k on it...

[jeffrey146]

Oh ok. You had me worried.

[P_Diako]

Probably your sending unit is bad and it's giving a faulty reading to your fuel gauge...

[terracide99]

it's a faulty fuel gauge. I had the same problem, and learned never to trust it. Instead I reset my trip odometer on each refuel, and start looking for shell when it hit 100. You can get it replace of course, it doesn't cost too much and doesn't seem too difficult from the guide i had read (never done it though)

[ak-s4]

Both my '05 B6 S4s would bury the needle past E before running out. I never did run it dry, but many times filled up with 16.5+ gallons. I also do believe there are dual tanks, one on each side of the drive line.

[mountainsnbirds]

I had the same problem and it took me forever to pin point the problem. My problem started the week after i had a new fuel pump and filter installed. At 1/4 tank of gas the car begins to sputter and turns off.
And every time after that i was out of gas at 1/4 tank. But the mystery continued because i could only ever put 11.5-12 gallons of fuel in when it was "out"
To make a long story short.....I believe(at least in my avant) the gas tank is a Saddle tank, and the hose connecting the two sides broke or stopped transferring fuel to the pump side. So there was always about 5 gallons remaining in the tank even when the car was "out" of gas.

Unfortunately, to fix this would require a tank removal.

My fuel gauge was not broken and the fuel sending unit(my first thought) was not bad either.

I hope this helps, good luck!

[tylerS]

start with cleaning off the fuel level sensor in each tank. easiest, cheapest, and will probably fix your problem

[0000 V8]

I have the same problem. It cuts out around 1/4 tank, but the computer display also shows about 90 miles till empty. Super annoying.

[dr.evil]

I have the same problem. It cuts out around 1/4 tank, but the computer display also shows about 90 miles till empty. Super annoying.

Same here. I just fill up with 200 on the trip odometer. Its harder to watch that than the gauge / DTE meter on the dash, and I've ran out a few times.

Anyone has a how-to on sender replacement?

[Lefthook]

I had the same problem and it took me forever to pin point the problem. My problem started the week after i had a new fuel pump and filter installed. At 1/4 tank of gas the car begins to sputter and turns off.
And every time after that i was out of gas at 1/4 tank. But the mystery continued because i could only ever put 11.5-12 gallons of fuel in when it was "out"
To make a long story short.....I believe(at least in my avant) the gas tank is a Saddle tank, and the hose connecting the two sides broke or stopped transferring fuel to the pump side. So there was always about 5 gallons remaining in the tank even when the car was "out" of gas.

Unfortunately, to fix this would require a tank removal.

My fuel gauge was not broken and the fuel sending unit(my first thought) was not bad either.

I hope this helps, good luck!

hmmmmmm.


My 04 Avant only ever takes about 14-15 gallons. I don't think I've ever gotten close to 16 gallons even when the DTE was showing zero.

[SoCalS4Avant]

start with cleaning off the fuel level sensor in each tank. easiest, cheapest, and will probably fix your problem

It's not often that Tyler and I see eye to eye, but I'm 100% in agreement. This is the best and cheapest option - and will likely fix what's wrong.

[tew]

When I bought my car, it did the exact same thing. I took it to the dealership and they found a pinched fuel line in the back. Evidently someone was back there before.

[JimmyBones]

If you have a vag-com then I would try running and output diagnostic check in the 17-Instruments. It should sweep the gauges from all the way left to all the way right then stop in the middle. If the fuel gauge goes too far to one side, doesn't go far enough to another side, or doesn't finish its travel correctly then you need a new instrument cluster. That is something easy to check and you don't get fuel on you because everything else will require basically opening the tank from openings under the rear seat.

hmmmmmm.


My 04 Avant only ever takes about 14-15 gallons. I don't think I've ever gotten close to 16 gallons even when the DTE was showing zero.

My 04 Sedan is and past 04 Convertible was the same way.

[gcoy]

Great info, How do I get to and clean the fuel level sensors? One on each side of the tank? Thanks g

[Rico750]

Great info, How do I get to and clean the fuel level sensors? One on each side of the tank? Thanks g

yeah i'd like to know this too, i got same problem... at 1/4 tank (by the gauge) i run out of gas

[gcoy]

Anyone??? have info on cleaning fuel level sensors? Thanks

[tylerS]

there's a diy on here if you search. you need to pull the rear bench, remove the two covers to access the tank. take a hammer and screw driver and hit the locking ring in a counter clockwise motion. remove the lids, then the senders. take a clean pencil eraser and clean the metal contact track.

[gcoy]

Thanks Tyler, I'll get to work

http://www.audizine.com/forum/showth...er-Replacement

http://www.audizine.com/forum/showth...l-sending-unit

[gcoy]

I pulled the bench and accessed the tank. My car only has one float and sensor, on the drivers side. I cleaned the contact and put things back together. Now I'll see if i run out of gas on the next 1/4 point on the guage... (05 Avant)

[blackedoutt]

Bumping this old thread. Was it sending units or pinched/cracked line? I found the OEM p/n for the lines from one side to the other of the saddle tank and don't think it would require removal of the tank to complete. Anyone else ever change those?

[Zhek18]

I pulled the bench and accessed the tank. My car only has one float and sensor, on the drivers side. I cleaned the contact and put things back together. Now I'll see if i run out of gas on the next 1/4 point on the guage... (05 Avant)

Hey I'm about 2 years behind but I'm just wondering what was the problem with your gauge, cuz I have a Quattro b7 and I'm having the same issue running out of gas at 1/4, I've been reading lots of post but nobody finishes lol, so what fixed your problem?

[TarlCabot]

you have 2 (two) sending units and one and/or both are bad... search and you will find how to test which one if not both you need to replace...

you will have a sending unit on both drivers and passenger sides, fuel pump is located on passenger side (for both B6 and B7) ...
idk what ^.^ is talking about :/

[gcoy]

I pulled the bench and accessed the tank. My car only has one float and sensor, on the drivers side. I cleaned the contact and put things back together. Now I'll see if i run out of gas on the next 1/4 point on the guage... (05 Avant)

Cleaning the float sensor worked for me. I have run my tank lower than 1/4 tank a couple times with no problems.
So, I guess I have fixed the issue, but just to be safe I always try and fill at 1/4 tank....

[Slow4]

Hey I'm about 2 years behind but I'm just wondering what was the problem with your gauge, cuz I have a Quattro b7 and I'm having the same issue running out of gas at 1/4, I've been reading lots of post but nobody finishes lol, so what fixed your problem?

** EVAP purge valve
** Fuel Level Sensor

I've had my Avant run out of gas on me several times when the gauge hits 1/8th tank. My first experience of this was quite horrible because I've never personally run out of gas and the symptoms led me to think of a completely different catastrophic outcome (you can seaRch for it). This is my theory on the 1/8th gas thing and how it related to the EVAP purge (feel free to dispute it):

Our engines are known for getting hot so what if by some off chance, the EVAP is affected, causing it to malfunction and not effectively purge a bloated fuel system of its gas fumes when the tank is half full or almost empty? All that pressure within your fuel tank might mess with your fuel level sensors. (If you don't believe there is a negative pressure in your fuel tank, open it up after a long hot drive, you'll here a hiss)

The EVAP purge sensors have also been known to go bad in B6 A4s; I would personally look at this $55 component before jumping on the $250 sending unit.

Reason why I don't think it's a faulty fuel level sensor: the gauge is working because it reads how much fuel you have from F to 1/8th before E. It also gives you a guesstimate of how many miles you have until empty via the ECU....FYI this doesn't necessarily mean the number is accurate but it gives you an idea of how far you can go before empty.


EDiT:

I pulled the bench and accessed the tank. My car only has one float and sensor, on the drivers side. I cleaned the contact and put things back together. Now I'll see if i run out of gas on the next 1/4 point on the guage... (05 Avant)

Haha, I haven't tried this yet. I just ordered myself a new EVAP from ECS too; wish I saw this earlier.

[blackedoutt]

Hot or cold, long or short drive, I still had this issue. I had a friend recommend to me to open the fuel cap to equalize tank pressure but that did not help. Still hoping some one can figure this out. In my case, new pump, lines checked (1 replaced), both senders cleaned and ohmed out fine. There is still the potential for the senders to be bad but I have not replaced them because I have no comfirmation that if sensor output doesn't match actual tank level it will cause the pump to suck air, I don't think it cares what the senders say if should still suck all the gas from the tank. I've popped the covers off the tank when it "ran out" still looked to be half full.

[vacsimile]

Tank routing, especially on the driver's side tank access (2nd sending unit and siphon pump side). It's either one of the lines getting knocked loose or the routing of the lines being wrong (likely due to one being disconnected) which causes the float to hang on the lines instead of dropping all the way down.

[gcoy]

Tank routing, especially on the driver's side tank access (2nd sending unit and siphon pump side). It's either one of the lines getting knocked loose or the routing of the lines being wrong (likely due to one being disconnected) which causes the float to hang on the lines instead of dropping all the way down.

Very good point

I had a hell of a time preventing the lines from hitting the float, & holding the seal in place, while closing the tank

[gcoy]

Very good point

I had a hell of a time preventing the lines from hitting the float, & holding the seal in place, while closing the tank

Come to think about it,,, This may have been my problem all along.
Cleaning my fuel level sensors maybe didn't fix my problem, but I'm sure it didn't hurt

[blackedoutt]

It is quite difficult to keep all those lines out of the way, but still that will only make the level read wrong. How could that make it so that it runs out of fuel with a lot left in the tank? Maybe I still have a line loose or routing wrong, any routing diagrams? It was all unhooked the first time I got in there so I made my best guess based on where things fit together.

[vacsimile]

It is quite difficult to keep all those lines out of the way, but still that will only make the level read wrong. How could that make it so that it runs out of fuel with a lot left in the tank? Maybe I still have a line loose or routing wrong, any routing diagrams? It was all unhooked the first time I got in there so I made my best guess based on where things fit together.

True, if the float is just hanging up it doesn't explain it running out of fuel when there is fuel. I've had this happen a few times and from what I can remember it's one of the suction lines that doesn't stay connected and that's what the float hangs up on. This also keeps fuel from being transferred to the passenger side where the pump is. The line connects to the bottom of the driver's side siphon pump at the bottom, and it's on a pivoted connection. It's easy to knock it loose when you install it. If all the lines are hooked up there shouldn't be interference with the level float, just make sure it can move freely without snagging on wires or lines. There are diagrams for the lines inside the tank but they're more of a schematic than a routing diagram.

[Slow4]

...well since I last posted in here, my fuel gauge has gone completely nuts. I filled up last night and on my way home (about 5mi from gas station), I went from Full down to half a tank. I'm currently looking at the fuel pumps and sending units but want to hold off for simple fixes like cleaning the sender sensors or as posted above, untangling lines. Like blacked out states, is there a diagram for these parts?

EDiT:

Nvm, found some useful links:

clean/test fuel senders -> http://www.audizine.com/forum/showth...l-sending-unit
checking the fuel return line -> http://www.audizine.com/forum/showth...-acting-stupid
better follow up to this thread by another member -> http://www.audizine.com/forum/showth...2C+fuel+sender

[Guitarmageddon]

Logic would say, that if you run it down to a quarter tank and it runs out, it should also then stay at the full mark and not move the needle for well over 50 miles of driving after filling to the full mark. Id pay attention to that just as much if I had this issue

[blackedoutt]

Argreed. Mine stays on full for over 50 miles for sure and " runs out" around half on the gauge with a true quarter left in the tank. I'm guessing something came unhooked and is both skewing my sender and not sucking fuel from the left side. Time to crack into the tank yet again.

[old guy]

Read post #3 in this thread: Clicky click

[Slow4]

...well since I last posted in here, my fuel gauge has gone completely nuts. I filled up last night and on my way home (about 5mi from gas station), I went from Full down to half a tank. I'm currently looking at the fuel pumps and sending units but want to hold off for simple fixes like cleaning the sender sensors or as posted above, untangling lines. Like blacked out states, is there a diagram for these parts?

EDiT:

Nvm, found some useful links:

clean/test fuel senders -> http://www.audizine.com/forum/showth...l-sending-unit
checking the fuel return line -> http://www.audizine.com/forum/showth...-acting-stupid
better follow up to this thread by another member -> http://www.audizine.com/forum/showth...2C+fuel+sender

Performing these checks today; will report back later

[Slow4]

As promised here's the update:

The fuel sending unit on the pump side seems to be running ok, put a DMM to it and it read 46.6/300 (per the link above).

The fuel pump looks to be in tact but I'm not sure if it's on it's way out or not. When I turn the ignition to ACC, fuel pump doesn't sound like it's cold priming, like it did during the winter; I got three repeating "putters" before it stops and I start the car.

The driver side fuel sending/fuel guage sensor was the one that sh*t the bed. When I opened the top, I saw the actual unit floating in the gas tank, on it's side.





How it's suppose to look:

[blackedoutt]

Well, looks like you found your problem lol. Can you please take a picture of how the lines are connected to the "Y" piece on the driver side sending unit/suction pump pick up? Mine has a brown piece that snaps to the bottom of the sending unit and I'm not entirely sure my lines are connected properly and the brown piece is snapped into the bottom of the sending unit right side up.

[Slow4]

[QUOTE=blackedoutt;9667251Can you please take a picture of how the lines are connected to the "Y" piece on the driver side sending unit/suction pump pick up? Mine has a brown piece that snaps to the bottom of the sending unit and I'm not entirely sure my lines are connected properly and the brown piece is snapped into the bottom of the sending unit right side up.[/QUOTE]



It's suppose to be right side up if I'm understanding you correctly. The entire sending unit on the driverside is suppose to hang at an angle.

It's why my gauge reading was completely off because it was floating in the tank versus suspending above the tank.