Fuel Gauge Vibrator got ya down? FAQ

[SGKent]

[mikedjames]

Problem is that the electronic stabilisers as fitted later by VW are still a bit basic, running components quite hot so these can also fail.

I have blown a more modern three terminal regulator chip off the dashboard of a 1990 Ford using nothing more than a loose wire on the ignition coil to provide high voltages.

Modern buck regulator modules would fit inside the can of the old vibrator and generate very little heat for $1 or $2 a go.
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Ancient vehicles and vessels

1974 VW T2 : Devon Eurovette camper with 1641 DP T1 engine, Progressive carb, full flow oil cooler, EDIS crank timed ignition.
Engine 1: 40k miles (rocker shaft clip fell off), Engine 2: 30k miles (rebuild, dropped valve). Engine 3: a JK Preservation Parts "new" engine, aluminium case: 26k miles: new top end.
Gearbox rebuild 2021 by Bears.

1979 Westerly GK24 24 foot racer/cruiser yacht Forethought of Gosport.
1973 wooden Pacer sailing dinghy

[SGKent]

[vwwestyman]

For whatever it is worth, I was recently working on my VW Cabriolet's fuel pump stuff, and noticed that the sending unit looked quite similar to the ones on a mid-'73 and up Bus.

Google says the full and empty resistance values are basically the same.

The Cabriolet sending unit has ports on the top for fuel inlet and outlet, and had a lift pump.

So it sure seems that with a little bit of work, one could use one of these sending units and eliminate the lower tank drain(s) of a Bus tank.
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Dave Cook

President, Wild Westerner Club

1978 Champagne Edition Westy, repowered to '97 Jetta TDI
1973 Wild Westerner
My Thing

[mikedjames]

That is excellent!


Just for reference in answer to a question from way back, at least some of the bimetallic strip vibrators are adjustable. E.g. on my 1974 bus.
Under a blob of paint there is a screw thread with two flats on it that you can grip with pliers and as you unscrew it, the average voltage drops.

If the voltage is already too low, then you have to carefully peel back the housing and take out the hardware. I had to clean the badly pitted contacts and then it began working again. Folded the metal cover over to put it back together.
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Ancient vehicles and vessels

1974 VW T2 : Devon Eurovette camper with 1641 DP T1 engine, Progressive carb, full flow oil cooler, EDIS crank timed ignition.
Engine 1: 40k miles (rocker shaft clip fell off), Engine 2: 30k miles (rebuild, dropped valve). Engine 3: a JK Preservation Parts "new" engine, aluminium case: 26k miles: new top end.
Gearbox rebuild 2021 by Bears.

1979 Westerly GK24 24 foot racer/cruiser yacht Forethought of Gosport.
1973 wooden Pacer sailing dinghy

[kpf]

Fantastic! Thank you!
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1971 Super Beetle

[megachaos]

...6 years later:

+12V---Vibrator (Voltage Stabilizer/Regulator to 5,1V)---Fuel gauge---Long wire---Fuel sender---ground/body:

We have 3 simple electromechanical components: Voltage regulator, Gauge, Sender. It is a more than 50 year's old design, but at that time it was very precisely and high quality made. Those times are gone! There is No Longer Available NEW Vibrator or NEW HQ Sender. So let's take a closer look at it:

1: Voltage regulator – Vibrator is perfect component, but it is more than 50 years old, so it will break. When it breaks, it can be repaired electrically, but it will definitely break again. When it breaks, it will pass the entire 12V voltage and that will fry the Gauge or Sender or both of them. The last thing you want in your gas tank is a burning Sender or heating coil! Electronic regulators (zener diodes, LM7805, LM317...) are great because they won't fry the Gauge or Sender. Unlike a working vibrator, which constantly switches the circuit ON and OFF, electronic regulators keep the circuit ON all the time. The electronic regulators must be in good working condition, otherwise the Sender still functions as a heating coil. Note: With the broken vibrator, I measured the current through the Sender from 0.1A to almost 1A! The Sender actually burned out and when I replaced it, the new one started burning too... (Pict.: Fried Original vs. Aftermarket sender)

Result1: I will leave out this voltage regulator/vibrator as a separate component!

2: Gauge – My Gauge still works, but it was almost fried and adjusting the Needle is now quite tricky.

Result2: No problem - if I want to omit the Vibrator/Regulator, I have to replace the Gauge.

3: Sender – The resistance wire was originally wound exponentially with high precision and quality material was used - This is No longer available. Aftermarket sender = Rubbish! The wire is wound poorly, linearly and breaks easily. Since another one cannot be bought, it is forced to use it. It is almost impossible to adjust it with a satisfactory result for the original vibrator and gauge.

Result3: The aftermarket sender must to be set up so, that it can be used successfully and does not function as a heater - so that it is completely Safe!

Process:
1. On the new Sender, we set the resistance range to 10 ohms for Full tank and approximately 80 ohms for Empty tank – by bending the stops. Then we bend the arm so that it copies the full stroke height in the tank of 200mm.

2. Now we can use an ohmmeter to measure the values between E and F according to the known values of the angles or levels. My aftermarket ClassicLine has: E=79ohm, R=67ohm, ¼=51ohm, ½=30ohm, F=10ohm. I made a cardboard jig for this, but the lines drawn with a protractor on the table are quite sufficient.

3. Making an electronic Gauge is easy thanks to the complete files from Pegor Karoglanian in the link below (except Uploading the programm to ATtiny85 – some issues are there with the right version of Servo libraries and also version of ATTiny Board installed in Arduino IDE). But Pegor shared all of the files, that You need – simply download it.

What You need:
a) A Friend with 3D printer (filament ABS, ASA, PA..., 0€)
b) Some money for electronic components (tme.eu, aliexpress, digikey..., cca 15€)
c) From Pegor downloaded files for made the PCB (pcbway.com, 6€ - for that price you actually get 10 pieces, so... 0.60€/each? ...hmm)
d) Some time for assembly this electronic Gauge and installation to dash (without old Vibrator and old Gauge). There is necessary to drill one hole (5mm) for new Gauge ground. (see Pict.)
e) Measure and edit the Sender resistance values in the SmoothBus.ino program for your new Gauge.
f) A Friend with Arduino UNO or MEGA as SPI programmer (0€) or buy Arduino Uno R3 with ATmega328P chip (20€)
g) After checking the functionality, if necessary, edit the servo position values in the program and upload again.

Programming with Arduino UNO R3 with ATmega328P chip:
1. Download and install „Arduino IDE“ to your computer (at this time is latest version 2.3.6).
2. Paste this link: http://drazzy.com/package_drazzy.com_index.json into IDE to File/Preferences-Additional boards manager URL´s column, click to OK and in IDE´s Boards Manager install ATTinyCore Boards by Spence Konde (v1.5.2).
3. Write/Upload to the Arduino UNO Sketch from File/Examples „11. Arduino ISP“. (see Tutorial on Youtube – link bellow)
5. PinUp the assembled gauge to Arduino UNO and set the IDE as programmer (see pict.).
6. Write to your new ATTiny85 the Bootloader.
7. Upload the SmoothBus.ino sketch to ATTiny85 via Arduino UNO as ISP.

Final: The voltage regulator is part of the new Gauge. The current through the Sender is in the range of 85mA at Full to 40mA for Empty. These are values similar to a system with a well-functioning original Gauge and electronic Regulator. The needle on the Gauge now shows accurate fuel values in the tank despite the poor quality of Aftermarket Sender.
This tutorial is also useful for me, because I struggled with uploading the program to the ATTiny for about 2 weeks (I saw ATTiny and Arduino for the first time in my life).

Links for download all the files and more infos:
1. Files for made the Gauge https://github.com/PegorK/SmoothBus/blob/V2/README.md
2. Tutorial for upload the programm with Arduino https://www.youtube.com/watch?v=sycSdI49hlY
3. Support for Arduino IDE software: http://drazzy.com/package_drazzy.com_index.json
4. Infos https://www.type2.com/library/misc/vwggauge.htm
5. Infos https://www.thesamba.com/vw/forum/viewtopic.php?t=693930

Note: I had to make some modifications to the Pegor's files: LED_1 and LED_2 should be orange (not red), the spacer should be 5mm thick for better gauge placement, the needle should be 4mm shorter, and my 3D model of the case is more durable.

Well - And (thanks to Pegor) now you have SAFE and fully functional Fuel gauge for 20~30€ – Hooray! ...and I have another 9 pcs for sell.

[Blue69Baja]

[Blue69Baja]

[Blue69Baja]

Another gauge, vibrator thread here that I started.

I like the regulator idea, needs to be adjustable. The sad is the meters avail now need to be adjusted too if one wants the gauge to be close to accurate.
Not sure if anyone knows that the original electro mechanical vibrators were adjustable....

https://www.thesamba.com/vw/forum/viewtopic.php?t=...p;start=20

Jim
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69 Baja with a 1914...
72 Super 100% orig...W/ factory air... 56,000mi
Even the spare is original..

[busdaddy]

Thanks, I have a Super beetle and a Datsun that are acting up at the moment, since you can't see it the new enclosure doesn't matter, I just want it to work and not come back, sounds like it'll do everything I need it to.
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Rust NEVER sleeps and stock never goes out of style.

Please don't PM technical questions, ask your problem in public so everyone can play along. If you think it's too stupid post it here
Stop dead photo links! Post your photos to The Samba Gallery!

Слава Україні!

[furgo]

There are many variations of this module. I've got the slightly less cheap version with current limitation and screw terminals for another application. Essentially it was cheaper and less time consuming to buy it than to solder discrete components.

Same chip, similar components. It's been working well for a few months, although admittedly I only use it occasionally.

All the SMD components should withstand vibration well. If it were to go on the bus, I'd put some glue or wax on the potentiometer once the output has been calibrated, though.

The only downside I'd see would be that it probably does not fit into the original enclosure, and a new enclosure for the module would have to be built.
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'79 Westy, P22 interior, FI 2.0 l Federal, GE engine (hydraulic lifters)

Decode your M-Plate

[busdaddy]

[furgo]

All clear now, I guess there is some more calibration to do once the sender is in the tank.

Thanks Telford and SGKent.
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'79 Westy, P22 interior, FI 2.0 l Federal, GE engine (hydraulic lifters)

Decode your M-Plate

[SGKent]

the way I calibrated mine was when the tank was out of the bus after cleaning it. I wired it up to the bus and used a yard stick thru the opening for the filler to raise and lower the float. The float would hit the top of the tank at about 3/4 indicated. I kept bending the arm until the float read full when it was all the way up, then set the bottom stop properly. Shinning a flashlight thru the filler I could also see about 1/4 and 1/2 so those were close too.

I found these photos in the gallery. Different variations of why they read differently. Don't like the idea the metal hoop touches / wears on the inside of the tank when it is full.

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George Carlin:
"Most people don't know what they're doing, and a lot of them are really good at it."

Skills@EuroCarsPlus:
"never time to do it right but always time to do it twice"

[telford dorr]

[furgo]

[SGKent]

calibrating the sender on a late bay (swing arm float) is a problem in part because the original floats were flat on the top. This allowed the float to rise higher in the tank when full. The new ones are round and hollow so they ride different. The arm must be bent to fool the sender into thinking the float is higher than it is or the gauge will never read over 3/4.

Everyone should be aware that the aftermarket vibrators are JUNK. The wires inside are twisted and not soldered, the electronic parts are just stuffed inside. There are also some cheap looking ones that say VW on them but they are forgeries because in no way do they approach the quality of a real VW one. Telford's if you can pay him to make you one, or a factory unit are the only two I would trust. The others will burn up your gauge eventually and NOS gauges are getting rare these days. This is a real one -

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George Carlin:
"Most people don't know what they're doing, and a lot of them are really good at it."

Skills@EuroCarsPlus:
"never time to do it right but always time to do it twice"

[furgo]

Just a couple of notes to complement this great thread, as I was working on this yesterday:

I've got one of the original but newer VDO voltage regulators, that is, a Zener diode + light bulb instead of a mechanical vibrator. Its VW part # is 211 919 051 A.

I observed that with no load, and varying the input voltage from 11.5 V to 14.4 V, the output voltage is 5.353 V (@ 12.6 V) +/- 0.03 V across the range.

However, when adding a load (i.e. the gauge and the sender), and given a constant input voltage of 14.4 V, the voltage regulation is not as rock solid:

• With empty tank (76,2 Ohm on the sender, min load), the regulator output is 5,332 V
• With full tank (5,8 Ohm(*) on the sender, max load), the regulator output is 5,116 V

That is, a voltage drop of 0,2 V from minimum to maximum load. Here is the wiring diagram of the sender, gauge and regulator system as a reminder.

On a separate note, while calibrating the system, I could not find an authoritative source for the sender resistance specs. There are a few places that list them, but all slightly different: 10-73 Ohm from Justkampers, 10-80 Ohm from VW Heritage and 10-70 Ohm from type2.com.

From the calibration exercise, I'd say that the 10 Ohm (full) and 80 Ohm (empty) specs seem to be what worked best for my (Late Bay) fuel gauge. The "full tank" resistance value seemed to be the most critical, and I had to bend the stopper tab on the sender to get a 10 Ohm reading and get the gauge needle to be on the full mark. At 76.2 Ohm for "empty tank", I could have adjusted it to 80 Ohm, but the needle was close enough to the empty mark and I left it alone. A few Ohms there don't seem to make as much difference as at the other end of the scale.

(*) Originally, the "full tank" value on my sender was 5.8 Ohm, which caused the needle to go way past the full mark. As mentioned, bending the "full tank" stopper tab to stop the float at 10 Ohm brought the needle back to the full mark.

[telford dorr]

Middle 1800's to now. Don't know before that.
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'71 panel, now with FI
'Experience' is the ability to recognize a mistake when you're making it again - Franklin P. Jones
In theory, theory works in practice; in practice, it doesn't - William T. Harbaugh
When you're dead, you don't know you're dead. The pain is only felt by others.
Same thing happens when you're stupid. - Philippe Geluck
More VW electrical at http://telforddorr.com/ (available 9am to 9pm PST)