Hi. After having a working fuel guage (new sender, new voltage stabiliser) working for a couple of months....now it goes up to just over a quarter and stops no matter how much fuel I put in. Any ideas...suggestions? Please.
Give up and just mentally work it out, it's not worth the stress Sent from my Pixel 3 XL using Tapatalk
Don't they do the opposite when they wear through? What happens on the gauge as the tank empties? When mine under read like that it was a poor connection between the voltage stabiliser and the instrument cluster. A bad earth on the instrument cluster to body would have the same effect. Mine "worked" but was half a tank under reading. Someone had actually deliberately gone to some trouble to insulate the regulator with cardboard which is just...wrong.
Thanks...gives me something g to check... Since installing the voltage stabiliser I have had to pull the instrument cluster forward to work behind. And I know when you do that you can 'knock' 'dislodge' something else without realising.
I agree it's unlikely to be the sender if the gauge won't go any higher - more likely to be insufficient voltage from the stabiliser. And that's a lot easier to check, unless you've got an inspection hatch to the tank.
in which case if you disconnect the two terminals on the sender and measure the resistance across them and you've got continuity even when the tank has plenty in, the sender is probably OK.
In the glum world, now you have current through the regulator and through the sender, the blackened crystallised resistance wire in the fuel gauge has now broken, so that every time the bimetallic strip gets heated by the current flowing through the wire in the gauge, it pulls on the wire and disconnects as it moves to indicate one quarter full.. Utter cheap junk, but it lasts 4 times longer than a bus was expected to last so its OK really. The prototype gauges with a proper moving coil meter on the other hand will work for another 50 years...
One day I will get my finger out and actually do the work on a microcontroller plus GM stepper motor mech that fits the same holes...
Sounds like the winding wire in the sender has broken at the 1/4 full mark. This would give your symptoms. The wire goes to a blind end at the full level as the current passes from the empty end of the winding wire, through the wire as far where the float arm terminal is at that moment, through the arm terminal and back to the circuit. I'm afraid repro senders can be rubbish. They very rarely have any resin protecting the winding wires. My bet is a new sender needed.
Not sure that's right Mark, the symptom of broken sender wire is up to full as normal then as the level drops and gets to the break it plummets suddenly to empty.
I'm not sure I agree. The current runs through the winding wire until the point where the float arm contacts, where it then goes to earth. The "full" end of the windings is a dead end. So if the arm is past the break, the result is open circuit. If the arm is under the level where the break is, it should work OK as the circuit is complete. I've got a few of these in bits now so could do photos to explain better - unless I've lost the plot and got this wrong.
£123,456...think i’d try and talk them down from that! Or is it some sort of Facebook pricing code for “make me an offer”? Sent from my iPhone using Tapatalk
I bow down in shame I had it arsebackwards. When it was in bits I held the float arm to it back to front which made me think it worked the other way round. Of course that couldn't possibly work for the resistances. I am a donkey, but a slightly wiser one now
I'm saving that one, thank you. I only knew the resistances at each end - that'll be a great help. Where did you get it please, as I'd like to get drawings for other models too? I've got three to rewind now with the half a kilometer of wire I bought for a fiver. Rainy day job.
Pinched from a thread on Samba. This is one persons persons findings. More nerdy stuff as the thread goes on. https://www.thesamba.com/vw/forum/viewtopic.php?t=693930
