Fuel Level Match

[JP_Pentz]

Good day to all can some one help me i am trying to get my fuel level and gauge to work together
got the VDO vw beetle gauge and (vdo sender aftermarket) need the right resistor for stable volts

If i add n 11.4ohm resistor it seems to work fine but the sender seems to heat up on the wingdings

[JP_Pentz]

Got it to work added n 220ohm resistor in line tanks!!

[retrovan]

Now you would need to fill in know amounts of fuel (5 lt at a time)

And see if its accurate.

best to set to be true on empty, as if incorrect at full, you do not have to push....

Herman

[JP_Pentz]

I set it to be true on half
Then ill just work with the rest did push in Desember

[Haans]

Get yourselves a backup!.....I have taken the revolutionary !!!! Decision to use a bird perch stickfrom a petshop!! And filled the tank with 5lt at a time and made markings on the stick witha soldering iron!!
Never pushed yet !!!

[Dawie]

That little unit for fuel gauge is not a simple resistor, its a regulator/voltage stabiliser.

[JP_Pentz]

Thank you Dawie
can you tell me what you mean regulator/voltage stabiliser??

[JP_Pentz]

Good day All

Dont now where Dawie went but let me explane what a dit on the regulator/voltage stabiliser.

You remove all the crap in there and get your self,
LED
Resistor 220 ohms
Voltage regulator (LM7810)

And there you go

The LED is just to show you it works

[Haans]

JP,..you seem to know a bit ,......not that I say the contributors don't know

Here's the question,......my ghia is converted to 12 volts BUT the fuel gauge and sender still 6volts,.....have added a 7810 regulator in the line,..butdid not help,......hence the stick.

NB the gauge still 6V,....but with my limited understanding the resistance is the important thing here,......me thinks
Sender unit,....also 6v ,....resistance is between 10 and 75 Ohms.

So how can I make this work with12 V ?

Yes!....I can buy aftermarket unit ,.....but then it looks different

Your view ?

Haans

[JP_Pentz]

Good day Haans hope you are well on this day well can you just explane to me way dit you add n 7810 and not a 7805 or a LM317

Here's the question,......my ghia is converted to 12 volts BUT the fuel gauge and sender still 6volts,.....have added a 7810 regulator in the line,..but did not help,......hence the stick.

[JP_Pentz]

Well Haans the basic concept: the float in the fuel tank drives a rheostat (variable resistance). The rheostat varies the current flowing into the fuel gauge on the dash, to high can burn the gauge to low can give falls reading. Inside the gauge, a tiny heating element responds to the rheostat current. When fuel level is high, the rheostat has approximately 10 Ohms resistance and current is at a maximum and the heater gets hottest. The heater is wound around a small bi-metal strip; as the heater warms up, the strip bends or "warps" When the tank is Empty, the rheostat has roughly 73 Ohms resistance

THE RESISTANCE IS JUST FOR LEVEL INDICATION CAN A CAN BE WRONG!

NB the gauge still 6V,....but with my limited understanding the resistance is the important thing here,......me thinks
Sender unit,....also 6v ,....resistance is between 10 and 75 Ohms.

[Haans]

Boet,.... not a clever as I look !!!! Question is how can be fixed to work ,......all I know is that I shared,..and from that you an see my knowledge is extremely limited with these kind of things!
Can it be fixed,if so...how ?,....otherwise it willbe the stick or an aftermarket set.

Regards
Haans

[retrovan]

Haans, as far as I know, the Ghia gauge is the same as the bus, it has no voltage regulator on it as the beetle has.

So if you get a Variable pot (potentiometer) you should be able to set it so it is near damit correct at empty.(even if it is 6v and your battery 12v)



VW always set their tanks to be true at empty, and runs over the full mark when full, (littlebit full same as a lotfull)

Even the generic fuel float one sold by Autquip will work on it.

Herman

[JP_Pentz]

Well Haans the way that a will fix it will start with the volts will replase the 7810 with LM317 you can make a constant volt driver from it (7805 jumps to 7810)

LM317
Resistor 1 (240ohm)
Resistor 2 (910ohm)
1/4Watt is fine

fuel gauges aren't ohm meters, they measure current based off resistance from the sending unit. Ohm's law still applies. If you double the voltage, that changes the current, thus changing the gauge reading.

Voltage = Current X Resistance

[german]

On the older golf and jettas cluster there is also a voltage stabiliser, dont know the values but maybe it would work.