Fuel Guage

[markholland8]

Hi All 72 beetle, the fuel guage can go from full to 3/4 full to half full in the space of about 3 seconds, also it can take a while to kick in. So my question is where would I start, thanks.

[ricaroo]

Here is a site that will help you diagnose your fuel gauge problem

http://www.midsouthvw.com/TechTips/tech_tip_FuelGauge.htm


Rick

[markholland8]

thanks Rick my next job.
Mark

[rockerarm]

Hi. At times the two small nuts will come loose, on the back side of the gauge, and create a resistance issue which is what the gauge recognizes. You will need to remove the voltage stabilizer to access one of the nuts. 10mm 1/4dr socket will suffice for this. Very small screw holds volt stabilizer to speedo housing.
Make sure your gas tank is properly grounded.
These are two diagnostic tips that cost nothing to check.
Hope this helps, Bill

[unclewede]

It can be frustrating. Over the weekend, the kid had been complaining that his gauge wasn't working again. I looked and it showed under 1/4. Then we went to the gas station and he was able to get a little over 4 gallons in there, and it was full again. I did a double-check to make sure he was actually getting a full tank in there. I really didn't want to start with adjusting that floater in the tank AGAIN.

But at least it shows him out of gas BEFORE he actually runs out, things could be worse. . .

[VW_Jimbo]

Cheap manufacturing sucks!

For what it is worth.

I have found that there is a voltage drop between the battery negative terminal, to the top plate of the sending unit. The drop is well over 2.5 volts. This indicates there is a lack of a good ground available to the fuel sending unit circuit.

Since this turns out to typically be a poor grounding issue, I take a test wire with two alligator clips. One clipped onto one of the screws at the sending unit, the other was attached to the ground point for the headlights. Then retest the fuel level. The results are immediate and satisfactory!

After that test, I will simply replace one of the plastic insulating washers with a copper washer from the oil sump stud. That allowed for a good ground path for the fuel sending unit, as it apparently does not have a great one, from the manufacturer.

Not sure if that helps, but that has been the issue with a few dozen vw's I have worked on over the years.

Good luck and post back if it helped you out!

Additionally, the aftermarket sending unit do not come calibrated for your tank. You must set the lever stops to the correct points. Then adjust the float arm by bending. I drain the tank and install the sending unit. Run the car, so that system voltage is available, and check that it registers empty.

Now put in 2 gallons, and make sure that it registers at the first white line of the "R". That way you have some gas to make it to the gas station (as designed by VW).

Then, when you have that tab bent correctly and the arm has been manipulated correctly. Remove the sending unit again, and tie a piece of string to the float arm end, down by the float. Thread that back up through one of the screw holes, or the opening. Set the unit as far down as you can into the tank and lift up the string, as far as the unit will allow. Go look at your gauge, and make sure it states full. If not bend that tab until it relays the correct reading at the gauge.

Empty the tank once again. Install the sending unit. Check the gauge. Readings should remain same as before. Pour in two gallons and recheck gauge for correct reading. If not, remove and readjust.

Do the same check with full. Go to the gas station and fill'er up. Check for a full needle!

After all of that, you will have confidence in the gauge and know when you should go to the gas station!

Again, good luck!
_________________
Jimbo

There is never enough time to do it right the first time, but all the time necessary the second time!