Broken Fuel Gauge

[MadMaxtheAxe]

Hey everyone,

My fuel gauge stopped working, so I bought a new one from TheThingShop.com and installed it but it's still not operating. I know the old fuel gauge was broken because I took it apart and the little wire inside was broken at a certain point.

Where should I go from here? I'm assuming I need to buy a new float mechanism, but are there any fuses or relays I might have to replace? Any way of testing these things?

Thanks a lot - The Axe

[Semper_Dad]

Note: Posting problem resolved. Apparently the porn detector didn't like the word "Vibra-tor" (without the "-".) Word now is Regulator

This issue has been gone over so many times you would think someone would have done a write-up on it already.

I am currently away from my 181 so I'm a bit limited on what information I can give you. But here goes;

Most of the info can be found here for troubleshooting the Beetle fuel gauge system. The 181 system is different in that it does not have the yellow wire mentioned in the guide. Instead, the sender is grounded through the fuel tank and the sending wire (brown) is directly hooked up to the fuel gauge.
http://www.midsouthvw.com/TechTips/tech_tip_FuelGauge.htm

The fuel gauge is Beetle and NOT 181 specific. There are no differences in 181 model years for the fuel gauge circuit. There are 3 major components to the fuel monitoring system.

1. The Gauge - Is a standard Beetle gauge. Used on all Beetles from 68 thru 79. Never hook up a gauge directly to 12VDC otherwise you will burn it up. You can test it briefly by applying no more than 6VDC just to see if the needle moves, but only briefly. See the “blip test” as outlined in the mid south link.

2. Gauge Vibrator - Mounted on the back of the speedometer. Essentially a voltage regulator. The original ones used a light-bulb as a load were almost mechanical in nature and even made noise thus getting the name Vibrator. New replacement Regulators may be solid state and will look different than the originals. The purpose of this device was to drop the voltage for the gauge AND dampen the needle movement caused when the fuel sender was sloshing around in the tank. Unlike Beetles where the Regulator plugs directly onto the back of the speedometer, the Regulator on a 181 is mounted backwards. This is so it will clear the defrost duct. Additional wiring completes the connections.

Inside a VW Fuel Vibrator

Works something like a Christmas light flasher. Cheap, but functional.

3. Fuel Sender - Mounted inside the fuel tank it's whole purpose was to send a signal in the form of a variable resistance from 10-80 ohms. Resistance value depends on the position of the float in the tank. Lower resistance = Full tank, Higher resistance = Empty Tank. Be careful of sparks near an open fuel tank anytime the sender has been removed. Power to the circuit should be off when installing, removing, and testing the sender. Disconnect the battery to be sure. In fact, testing the sender should be done far away from the car on a workbench. Sparks can be generated using a standard Ohm meter resulting in fire!

This is a simplified current track for the fuel gauge system

Power is supplied to the circuit when operator turns ignition key to "On" position. Power is then applied (via Black Wire) to the hot side of Fuse 1. Note: This is the hot unfused (input) side of the fuse box therefore the gas gauge circuit is not a fuse protected circuit. The voltage (12VDC) is then applied (via Black Wire) to the Regulator which reduces the voltage to a range of 5-6 VDC. Output of Regulator is connected to fuel gauge. Excess voltage is burned up and sent to ground by using a load resister, light bulb, or other solid state device. Note: Regulator must have a good ground in order to function properly. Normally, mounting it on the back of the speedometer is sufficient. Fuel sender with its variable resistance is connected (via a Brown Wire) to the other side of the gauge.
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Walküre Restoration Thread: https://www.thesamba.com/vw/forum/viewtopic.php?t=737492

[tmitoraj]

If the wire burned out in the fuel gauge make sure you have a vibrator connected to the fuel gauge. If not, 12V goes in to the fuel gauge and burns out the wire. Ask me how I know. See my questions a few weeks ago as I had similar problems.

[MadMaxtheAxe]

Thanks, I read your older post and if it is the vibrator then I suppose I'll have to get a new one. The only problem is I'm not sure what and where it is. I looked up some picture and I believe it's the small rectangular relay looking piece that one of the wires from the fuel gauge hook into. It seems, if this is the right part, that it is hooked onto the back of the speedo by a type of pin or bar that sits off the back of the speedo cluster. Does that sound right? Got a picture of yours in it's place by chance for me to reference from?

Thanks

Also I just saw a picture of a beetle restoration where a guy was attaching a new vibrator right up against the back of the fuel gauge. It looked as if the prong on the vibrator went right into the appropriate prong on the fuel gauge. If the part I think is the vibrator is in fact the vibrator, mine has a small wire that attaches from one prong to the other.

Is it supposed to be right against the back of the fuel gauge? I will put a ling to the picture here

http://www.vwtrendsweb.com/tech/0410vwt_1971_beetle_super_project_part_15/photo_17.html

[sdwalter]

The fuel gauge vibrator mounts upside down on the Thing in order to clear the defroster ducting. See the picture from the gallery below.

[MadMaxtheAxe]

Indeed I have seen quite a few inquiries about this issue. Thanks for helping out. This information is huge. The pictures are priceless.

Picked up a new vibrator and sending unit just to be safe. Started with the vibrator, still not working. Put in the new sending unit and, bingo, fuel gauge is now fully functional.

I was able to put it in place right side up, but it's a little snug for my liking. To much actual vibrations from the car and who knows if it will last. Gonna go back and put it in upside down like your picture shows.

Thanks for all the help, once again.

-max

[doublecanister]

Hey Max,

just curious about this fix,

did you check to see if your "float" actually "Floats"?

Sure glad you fixed it but I ran into the same issue upon purchacing my 73 thing, the sender actually worked but always showed empty.

upon testing electriclly it functiond but the float was cracked in many places (old black plastic) AND thus it sank showing empty.

I've had this SAME issue occur on quite a few vehicles in my time, both with brass and plastic floats.

anyways just mentioning if anyone ever finds this to check.
That and it still mystifys me that after 4years it still works after fixing the plastic float via a melted black zip tie! MacGuyver to the rescue!

Glad you fixed it bro!

T
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2020 - Mustang Eco Boost [High Performance]
1973 - Thing
1966 - Mustang GT- Fastback
1951 - Ford F1 pickup Flathead V8

[6BUG3]

I had this issue on my 68 bug but the sender unit seems to have melted at the full tank mark so it doesn't give a reading until about 1/2 tank.

I have always had a leaky sender unit seal so I got a new gasket recently. Installed it and filled up the tank to test it. It holds alright but since I've never filled the tank before for fear of leaks the float had never had the chance to get that high. When It got up there it shorted out and sent the entire 12v to the vibrator which overheated, fried, cooled down, completed the circuit, and fried my gauge. I really shouldn't buy from wolfsburg anymore, all their parts are crap.
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1985 Tin Top Vanagon
Savanna Beige Metallic

[Hyatt181]

This is older thread but I am looking for the fuel gauge vibrator solid state version.
I installed one in my thing back in 99 but am trying to find one for another thing.
We installed one of the new ones in my dads and had it fail. Also had the empi stock looking sending unit fail. The float stopped floating and the thing is stuff compared to an original.

[6BUG3]

I bought mine from my LPS. I'm sure they can order them still and may be able to mail order it to you. They're small car connection in hesperia CA. 7602449811 give them a call.
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1985 Tin Top Vanagon
Savanna Beige Metallic