And thank you again for your postings on all you do.... Even tho I am a shade tree mechanic what you give us is very valuable information. Your electrical analytics and drawings are top notch. People have not discovered your offerings and they do suffer for that.
FYI: the box that's between the incoming hot line and the gauge input is a "vibrator". It's an *average* voltage source. (It does not produce DC as someone else in this thread claimed.) It produces output that cycles on and off quickly (a few seconds off, a few seconds on sort of thing) and the *average* is some reference voltage that makes the position of the gauge be correct. The reason for it is that the electrical system (particularly before Beetles went to alternators and their generators had mechanical regulators) would vary from maybe 11.5 to up to 15 volts. The vibrator compensates for that. At idle, the voltage is low, so the internal heater in the vibrator heats up the contact more slowly, so the output is on more than it's off. When the voltage is high, the heater heats up the bimetallic strip very quickly, so it's on for less time, but it takes exactly the same amount of time to cool off. So the *averaged* voltage is roughly constant. This means that the gas gauge doesn't fluctuate up and down as the engine goes from cruise to idle to cruise.
You can measure it with a voltmeter if you measure between ground and that contact that's between the vibrator and the gauge. You'll see that contact go from off to full battery voltage to off, on and off constantly.
My tractor suffers from an odd shaped tank. I thought the guage was messed up and found the engineers most likely focused on empty because full is off, but guage and sender ohmed out good. Thanks for the insight.
the three prong box is a vibrator. It produces 5 vdc for the gas gauge circuit. it is a cheap way to produce a reduced voltage from a higher voltage, My experience with a new gas sender required a higher voltage to work with the new aftermarket sending unit due to the higher resistance aftermarket gas gauge you mentioned. . My gauge never went past 5/8 full I built a voltage regulator and placed it in inside the vibrator box. set it to 6.5 vdc to drive the needle further to the right. I realize that is beyond the capability of many mechanics, another way to increase the output of the vibrator would be to place a diode between the ground prong on the vibrator and the chassis connection of the car. A silicon diode, should give you about 0.7 VDC increase to about 5.7 VDC. To get more selective, a reverse biased Zener diode of the desired voltage minus the 5 VDC of the vibrator installed in the same way will dial the gauge right in.
hello, I am buying a 72 super in 2 weeks, the gas guage does not function. what is the best way to determine whether its wires, the guage, or the sending unit that needs replacing?
Hey Chris question please I’m not working on a VW but a 63 C-10. I bought a new gas and sending unit, but the gauge, which was working, isn’t reading properly or I have a faulty sending unit. I have ohms on both but during my bench test when connecting pwr the gauge pegs out. I tried switching terminals on the gauge& it still pegs out. Any suggestions? Thank you in advance
You have stumbled into the worst issue that aftermarket parts for a 69 and up VW, any type, has occurred! You showed exactly what the issue is... OEM gauge has a way lower resistance that the aftermarket gauge! The only way to make the aftermarket gauge work is to increase the voltage at the input to the gauge! As you show, 5.1 will not make the aftermarket gauge swing to full.. All VW senders, any type, Std Beetle, Super, Gia, Buses, Things, will be around 10 ohms at full and around 70 for empty. 10 ohms F, 20 1/2, 33 1/4 47 R and 70 for E The OEM vibrator nor the aftermarket plastic/metal called a vibrator is not a vibrator it is a regulator. Good job at being curious how the gauge system works... BTW, the OEM gauge you measured resistance was 13... It should be about 18. From my experience this means that the gauge nichrome wire has partially shorted, reduced resistance. This is usually caused by shorting the sender wire to ground/chassis to see if the gauge will read full! One should not leave that wire shorted more than about 5 seconds! Here is one of my videos showing your issue. My sender is for a Beetle but the residences are the same. You will see from my video exactly what you were seeing. The only resolution we have right now to fix the low fuel reading is to raise that voltage. I have tried to make the vendors that sell these things to go after the manufacturers.. Also have an engineering friend in Sweden that has been in communications with the mfg of the gauge and the senders! They are non responsive. Here is one of my videos showing the same issue you showed: ua-cam.com/video/BGv18l_uJJY/v-deo.htmlsi=FQZzzNF5zsMJxImJ Here is an explanation for the operation of the vibrator. ua-cam.com/video/29I3oeVjWHI/v-deo.htmlsi=ubTqihk9K0tbn3h0&t=214 Jim.
@@chriscraft77022 i usually learn stuff like that way out in the desert 100 miles from nowhere, just my kinda luck, but i'm almost 70 and have had numerous bugs in my life and enjoyed them all, I've also always worked on them myself feeling like nobody is gonna do it better for money than i can do it for myself for free. now that i'm older and wouldn't mind somebody doing somethings for me , can't find anybody who knows how to work on them or doesn't want to mess with it for whatever reason.....nothing {almost} is more embarrassing than running out of gas in a bug, at least back in my day and i've done that too, live long and enjoy the ride!.
Dude how do you put the needle back in was doing some testing and accidentally pulled it out now every way I try to put it back together it's just hanging..
You also have to take into account that most gas tanks are not perfectly symmetrical. For example, fuel could be exactly 1/2 way from top to bottom, but not be 50% in volume. I'm sure the OG engineers calculated that into the gauge...
Hi.!Could you show me more about fuel gauge at beetle 74 and I have a problem with it If you could I be pleased.Thank you,greetings from english teacher from Kosova.!
And thank you again for your postings on all you do.... Even tho I am a shade tree mechanic what you give us is very valuable information. Your electrical analytics and drawings are top notch. People have not discovered your offerings and they do suffer for that.
Awesome video! Now I know how to fix my 1972 gauge. Been a mystery for 35 years!
This is the best explanation video so far. Thanks
FYI: the box that's between the incoming hot line and the gauge input is a "vibrator". It's an *average* voltage source. (It does not produce DC as someone else in this thread claimed.) It produces output that cycles on and off quickly (a few seconds off, a few seconds on sort of thing) and the *average* is some reference voltage that makes the position of the gauge be correct. The reason for it is that the electrical system (particularly before Beetles went to alternators and their generators had mechanical regulators) would vary from maybe 11.5 to up to 15 volts. The vibrator compensates for that. At idle, the voltage is low, so the internal heater in the vibrator heats up the contact more slowly, so the output is on more than it's off. When the voltage is high, the heater heats up the bimetallic strip very quickly, so it's on for less time, but it takes exactly the same amount of time to cool off. So the *averaged* voltage is roughly constant. This means that the gas gauge doesn't fluctuate up and down as the engine goes from cruise to idle to cruise.
You can measure it with a voltmeter if you measure between ground and that contact that's between the vibrator and the gauge. You'll see that contact go from off to full battery voltage to off, on and off constantly.
My tractor suffers from an odd shaped tank. I thought the guage was messed up and found the engineers most likely focused on empty because full is off, but guage and sender ohmed out good. Thanks for the insight.
the three prong box is a vibrator. It produces 5 vdc for the gas gauge circuit. it is a cheap way to produce a reduced voltage from a higher voltage, My experience with a new gas sender required a higher voltage to work with the new aftermarket sending unit due to the higher resistance aftermarket gas gauge you mentioned. . My gauge never went past 5/8 full I built a voltage regulator and placed it in inside the vibrator box. set it to 6.5 vdc to drive the needle further to the right. I realize that is beyond the capability of many mechanics, another way to increase the output of the vibrator would be to place a diode between the ground prong on the vibrator and the chassis connection of the car. A silicon diode, should give you about 0.7 VDC increase to about 5.7 VDC. To get more selective, a reverse biased Zener diode of the desired voltage minus the 5 VDC of the vibrator installed in the same way will dial the gauge right in.
thank you for that info.. so what is my 2 prong on my 72 Beetle?
hello, I am buying a 72 super in 2 weeks, the gas guage does not function. what is the best way to determine whether its wires, the guage, or the sending unit that needs replacing?
Hey Chris question please I’m not working on a VW but a 63 C-10. I bought a new gas and sending unit, but the gauge, which was working, isn’t reading properly or I have a faulty sending unit. I have ohms on both but during my bench test when connecting pwr the gauge pegs out. I tried switching terminals on the gauge& it still pegs out.
Any suggestions?
Thank you in advance
they might use the old resistor or be internally resisted in which do not use the old resistor
You have stumbled into the worst issue that aftermarket parts for a 69 and up VW, any type, has occurred!
You showed exactly what the issue is... OEM gauge has a way lower resistance that the aftermarket gauge!
The only way to make the aftermarket gauge work is to increase the voltage at the input to the gauge!
As you show, 5.1 will not make the aftermarket gauge swing to full..
All VW senders, any type, Std Beetle, Super, Gia, Buses, Things, will be around 10 ohms at full and around 70 for empty.
10 ohms F, 20 1/2, 33 1/4 47 R and 70 for E
The OEM vibrator nor the aftermarket plastic/metal called a vibrator is not a vibrator it is a regulator.
Good job at being curious how the gauge system works...
BTW, the OEM gauge you measured resistance was 13... It should be about 18. From my experience this means that the gauge nichrome wire has partially shorted, reduced resistance. This is usually caused by shorting the sender wire to ground/chassis to see if the gauge will read full! One should not leave that wire shorted more than about 5 seconds!
Here is one of my videos showing your issue. My sender is for a Beetle but the residences are the same.
You will see from my video exactly what you were seeing.
The only resolution we have right now to fix the low fuel reading is to raise that voltage.
I have tried to make the vendors that sell these things to go after the manufacturers.. Also have an engineering friend in Sweden that has been in communications with the mfg of the gauge and the senders! They are non responsive.
Here is one of my videos showing the same issue you showed:
ua-cam.com/video/BGv18l_uJJY/v-deo.htmlsi=FQZzzNF5zsMJxImJ
Here is an explanation for the operation of the vibrator.
ua-cam.com/video/29I3oeVjWHI/v-deo.htmlsi=ubTqihk9K0tbn3h0&t=214
Jim.
Is that resistor a result of VW originally running on a 6volt system not a 12volt?
it stops the needle from bouncing around on GM so I would assume the same
r is for reserve, usually indicates 1 or 2 gallons left at most.
I learned that the hard way and got stranded no gas a mile from my house
@@chriscraft77022 i usually learn stuff like that way out in the desert 100 miles from nowhere, just my kinda luck, but i'm almost 70 and have had numerous bugs in my life and enjoyed them all, I've also always worked on them myself feeling like nobody is gonna do it better for money than i can do it for myself for free. now that i'm older and wouldn't mind somebody doing somethings for me , can't find anybody who knows how to work on them or doesn't want to mess with it for whatever reason.....nothing {almost} is more embarrassing than running out of gas in a bug, at least back in my day and i've done that too, live long and enjoy the ride!.
Dude how do you put the needle back in was doing some testing and accidentally pulled it out now every way I try to put it back together it's just hanging..
Where’s the Chevelle videos? 😂
i still have it.. that car wasn’t getting views.. that’s what happened.. it will pop back up when I get the paint booth done
Thank you for the video good
Niceeeee video.
You also have to take into account that most gas tanks are not perfectly symmetrical. For example, fuel could be exactly 1/2 way from top to bottom, but not be 50% in volume. I'm sure the OG engineers calculated that into the gauge...
thank you.. yes, I noticed that
Hi.!Could you show me more about fuel gauge at beetle 74 and I have a problem with it If you could I be pleased.Thank you,greetings from english teacher from Kosova.!
Just bend the sending unit rod. 6 screws and it's out. very easy.
This was “engauging”
😒
Come to find out they sent me the wrong sender unit. I need 0-30 ohms they sent 60-120 ohms
Thanks man
En español
😅 ince