Fuel gauge

Cold Steel · Samba Member Joined: March 11, 2010 Posts: 587

My fuel gauge has been working fine until now. What's occurring is the gauge in the instrument panel is showing half full. Oh wait, gas so expensive I don't have the money to fill it up all the way:)
I filled the tank all the way up and it still only showing half full.
What should be my troubleshooting steps?
Thanks
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oc2bc · Samba Member Joined: August 24, 2010 Posts: 88

I'm watching this topic with interest as mine functions (or doesn't function) the same way. I noticed the first time filling up after buying the van and it's on my list of things to do.

Corwyn · Posted: Wed Mar 30, 2011 8:31 am Post subject:

I had the same issue a month or so ago.

I dropped the tank, checked the sending unit (thought it might be a grounding issue), and traced the wires all the way forward. Nada. Maybe the gauge itself (20+ years old) is dying.

When I drive up steep hills the level goes waaay down; when I drive downhill, it goes back up. Go figure!
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reluctantartist · Posted: Wed Mar 30, 2011 8:32 am Post subject:

It may be the voltage stabilizer on the gauge pod.

http://www.busdepot.com/details.jsp?partnumber=357919803
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WAgrower · Posted: Wed Mar 30, 2011 8:47 am Post subject:

does it move at all when you turn the van off? what about your voltage stabilizer if the gauge twitches then it could be the stabilizer?

If it's not stuck then take a multi-meter and read the voltage at the gauge then read the voltage at the sender (or as close as you can get)
They should read the same or within .5v. If not then your issue is in the wire.
If they read the same then your issue is with the gauge or sender.

If it's the wire it's an easy fix, if it's the gauge or sender it's a little more tricky.
to test the sender you can measure the resistance of the sender circuit as the tank drains. The resistance should increase as the tank drains, and be near 0ohm with the tank full. You could measure it then drive for 20min and measure again, and the resistance should increase.
To test the gauge you could theoretically hook it up to a 12v source with a potentiometer to check if it's responding; as you let more current through it should read higher.. Not sure about this test however the gauge may work off a lower voltage! I've never had to trace mine but the circuit is simple.

Cold Steel · Samba Member Joined: March 11, 2010 Posts: 587

ok so i have completed a few more tests.
1. the guage works just not properly
2. the gauge goes up and down but no all the way up
a. Test one the fill up. So I thought I was running low. I put fuel in until I heard the click. Ahhh its full but wait is it? Lets go for some more clicks. Oh...fuel is no coming out of the nozzle. (sorry epa I did clean everthing up)
b. With a FULL tank, the guage read 3/16 below the line.

The needle should be above the line at this point not below it.

So...I have a theory I dont want to find out about. I think some how the fuel sender inside the tank has malfunctioned. I think it is stuck or something. Not wanting to go inside the tank yet.

I am will test the others suggested in the thread. Smile

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MakeFast · Posted: Mon Apr 04, 2011 2:54 pm Post subject:

Posting to watch, I'm in the same boat.
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Ahwahnee · Posted: Mon Apr 04, 2011 3:07 pm Post subject:

pushkick · Samba Member Joined: August 09, 2007 Posts: 1366

if you unplug your sender unit and plug a new one with out removing your
tank you could test your gauge system to see how it is working. the sending
unit is basically a reohstat i thnk.
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pioneer1 · Posted: Mon Apr 04, 2011 4:38 pm Post subject: gas tank

Hi:I think your readings are pretty normal. I had a new tank, sender unit and replaced the voltage stabilizer. My gauge still never showed full, and as the gas moved back and forth the gauge went up and down-it is just a float ...More important was that it did show empty
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AndyBees · Posted: Mon Apr 04, 2011 5:28 pm Post subject: Re: gas tank

DAIZEE · Posted: Mon Apr 04, 2011 5:30 pm Post subject:

Mine shows up now but I think it will need to be changed someone said because its now diesel. So is a diesel sender different than a gas and if its a float would that make a difference? When I have a working van I reset the tripometer at every fill up and carry a 5 L tank.
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AndyBees · Posted: Mon Apr 04, 2011 5:52 pm Post subject: Fuel level sending unit

Cold Steel · Samba Member Joined: March 11, 2010 Posts: 587

Dude,e My gas gauge needs to be tighter than my accountant when it comes to reading my gas. F...anything else. My shiznezzle is broken. Its so far off from what should be the normal.
Again, I am still hunting. I have lots of test still to conduct. I will find the proper answer...Bare with me!!!
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Cold Steel · Samba Member Joined: March 11, 2010 Posts: 587

ok so I filled up today again and it was pretty low. Now this was interesting. When I opened the cap, a vaccum was created. It slurped air into the tank. I didnt have enough to fill the tank but I through a 50 at it. It registered pretty in the neighborhood of where I thought it should be.
I am not sure how this affects anything but its the only change that I have made.
I am wondering if the white vents are working properly?
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BC Westie · Posted: Thu Apr 07, 2011 10:45 pm Post subject:

Start simple and check for corrosion around your voltage stabalizer.

I dropped my tank, changed the sender unit, fuel gauge, only to find that when I looked at my voltage stabalizer it had a little blue corrosion where it attaches to the circuit board. Cleaned it up and all of a sudden I had a working gauge.

I beleive mine had a similar action. Filled the tank and the gauge would only go to 1/2 and then go down and sit on the red the rest of the tank.
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1981 Westfalia 300,000kms
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chardog1971 · Posted: Sat Apr 30, 2011 8:17 am Post subject:

My gauge doesnt work either. I should say it works onlw when I drive over bumpy roads.it seems to be fairly accurate when its on. I fill up alot for two reasons 1) I dont like to walk long distances in -20 degree weather. 2) it reminds me to check my oil often. I am thinking it is the ground or a loose connection at the sending unit. Still snowing out so I will keep it full untill it gets nicer out. Dammed climate change!
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Cold Steel · Samba Member Joined: March 11, 2010 Posts: 587

ok so!!! Tests have been done. Ok I have since filled 4 tanks of fuel. I have found these results. If the tank is opened, and air rushes in. I can fill up all the way. If not, I get a false fill, meaning it doesnt go all the way.

I checked the voltage stabilzer. When I did, i used my mult meter, i placed it on 50 dcv and started my test. WOW! I was watching my needle move around and BAM out of the corner of my eye. SMOKE!
Now my turn signals dont work? What did i do wrong? Was I suppose to check with omins?

THANKS
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mreuter · Posted: Mon Apr 27, 2015 11:42 am Post subject:

Was this problem ever solved ?

Steve M. · Posted: Mon Apr 27, 2015 8:51 pm Post subject:

faded away into the ether.
if you have the problem check your Voltage Stabilizer first off.
For some strange reason known only to other people than myself, VW decided to use a fuel gauge that works on 10 volts in a vehicle that operates on 12 volts.
it is located on the back side of the instrument cluster. Do a search in the forums, I'm sure there is more threads all about it.
all the other remedies are worth trying, but if you do not have the time to check them then check your fuel mileage instead. It will be more accurate than the fuel gauge!
Just get into the habit of resetting your odometer every time you fill up and do the math the next few times you fill up to figure out how many miles you're going to get per tankful of gas. Also do not reset the odometer while the vehicle is moving-you will break it.


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