Conversion to a electric fuel gauge and sender?

[toxicavenger70]

I have a 65' that I just installed a 68' speedo/fuel gauge into. I have everything hooked up, the sender (tube style/electric) grounded. It is working. The issue is the gauge only reads half fuel. When I unhook the gauge then ground it, the gauge does read full. When I unhook it moves to empty.

I have done some reading and multiple places list a few different sizes (I wasn't aware of that beforehand). I currently have a 7 1/2 version installed in my car. I have seen a 280mm version and a 310mm.

Any idea what size would be needed in a stock 65' tank?

Thanks ahead of time.

[AirHead1966]

I am sure there are other ways to do it, but I would do it electronically.

Get a potentiometer (3Watt should be fine).

Cut the wire from the sender and attach it to the Vcc or input of the pot. Connect the other end of the cut wire (that goes to the gauge) to the output of the pot. Ground the ground terminal of the pot.

Fill the tank and slowly adjust the pot until it reads full.

[TDCTDI]

Is the sender new or an old one?

If new, there has been issues with aftermarket senders not having the same resistance as factory senders.

If the sender is an old unit, it may need to be repaired, here’s a great how-to from the bay window forums...
https://www.thesamba.com/vw/forum/viewtopic.php?p=7706426#7706426
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[toxicavenger70]

[toxicavenger70]

[VOLKSWAGNUT]

Take the sender out of the tank...

Use a jumper circuit from the sender mount base to the car ground.. being sure to leave the sender circuit to the gauge attached.

Test the range of gauge readings by sweeping the float arm...
If the gauge reads empty when the float is down and full when the float is up.. the issue is with the tank ground or float arm movement or position in the tank. If the gauge doesn't match float travel.. there is a mismatch between gauge and sender..

The sending unit MUST BE grounded properly. It may be necessary to route an extra ground to the sender base with an eyelet under a sender screw. It is real important to not use the screw insulator on that grounding screw as well.

.
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[HBRag]

VDO stand is 10-180 Ohm range. There are a bunch of different standards, so the gauge and sender have to match. Are you sure the sender range is correct, and not a GM or Ford standard which may end at 90 Ohms?

[toxicavenger70]

[toxicavenger70]