TheSamba.com :: View topic - HOW TO: Revive your fuel gauge sender for $1 FAQ

Sat Nov 02, 2013 5:33 am

Subscribed, thanks for the diy, we had a similar write up on a motorcycle forum repairing Suzuki senders.

http://www.ebay.com/itm/Nichrome-resistance-wire-3...33853e112d

Sat Jan 11, 2014 12:21 am

Many thanks for the tute.. my sender coil is damaged too.

Fri Apr 18, 2014 8:28 am

Very interesting thread. I will try replacing the resistance wire the next time. In my case a new repro Mexican sender was very inaccurate, poorly made, and the float banged against the tank when near full. Drove me mental and replaced it with a sender using parts cannibalized from several. Gauge would only read 3/4 when full. Others seem to have had this problem. Replaced the wire from the sender to the gauge with a heavier wire. Works perfectly now...

Fri Jul 04, 2014 5:16 am

After fighting with the POS repro sender I bought, I thought I'd give this a try.....

Before.....

After.....

Happiest my gauge has been to date!

The wire I ordered had been rolled on a cardboard spool, but running it a couple of times through pinched fingers smoothed out the kinks. Whole job was done in about 1/2 hour. I started by pre-measuring, but came up short, probably due to the different shape. After that just used a continuous piece until fully wound. Also didn't use epoxy.
Been a few months now and working great. Thanks Daverham!

Wed Jul 16, 2014 10:31 am

Very good tutorial, thank you.
My last replacement sender only lasted a couple months before the contact cut through the wires, so I rebuilt it.
A handy source for resistance wire in my area is e-cig/vape shops. They're popping up all over. The store I went to didn't carry nichrome, so I bought some 32 gauge kanthal. That was the thinnest they had.

32 gauge kanthal has half the resistance of 36 gauge nichrome, and 70 ohms worth is a bit over 5 feet. I bought enough wire for two tries in case I messed up, which I did. The turns of wire had to be closely spaced to get all 70 ohms to fit on the board. On my first try I did not get it all on before I ran out of room. The edge of the board puts sharp kinks in the wire that don't come out well, so unwinding and rewinding, the thing looks like hell. I would say that in order to get good results, you need to smooth out the wire pretty well, plus it will be easier to work with. In the end 32 gauge worked just fine, but if there is a next time I will use 36 gauge. Also, I was initially concerned about the turns of wire contacting each other, but that doesn't seem to be an issue.

Sun Mar 08, 2015 1:34 pm

Hello everyone

I saw your post on his topic I'd like to take the opportunity to ask you a question… I am not sure if my fuel gauge is working properly. How can I checked it to know if it is working ok or not? When the tank is nearly empty the gauge signal does not show at all it is hiding completely and when I fill up it shows but I am not sure it is accurate. I am off on a long road trip through Europe and would like to have this sorted OK before I go. Would you be able to tell me what I should do to see if it is working properly?

Thanks
Ian

Sun Mar 08, 2015 1:35 pm

Hello everyone

I saw your post on his topic I'd like to take the opportunity to ask you a question… I am not sure if my fuel gauge is working properly. How can I checked it to know if it is working ok or not? When the tank is nearly empty the gauge signal does not show at all it is hiding completely and when I fill up it shows but I am not sure it is accurate. I am off on a long road trip through Europe and would like to have this sorted OK before I go. Would you be able to tell me what I should do to see if it is working properly?

Thanks
Ian

Sun Mar 08, 2015 1:49 pm

Ian xuereb wrote: Hello everyone

I saw your post on his topic I'd like to take the opportunity to ask you a question… I am not sure if my fuel gauge is working properly. How can I checked it to know if it is working ok or not? When the tank is nearly empty the gauge signal does not show at all it is hiding completely and when I fill up it shows but I am not sure it is accurate. I am off on a long road trip through Europe and would like to have this sorted OK before I go. Would you be able to tell me what I should do to see if it is working properly?

Thanks
Ian

Ground the sender from the tank to the gauge. If the gauge moves all the way over to full when you ground that wire, then your sender is bad.

Fri May 01, 2015 8:49 am

busdaddy wrote: There's just 1 looong wire that is gounded to the top at one end, goes all the way to the bottom and comes back up the other side where it attaches to the gauge terminal, the float moves a contact that bridges the wire and changes the resistance. Here's type 3 one, different length but same principle:

And what goes wrong on these type units? The wire, or are their some brushes that contact on the shaft?

Fri May 01, 2015 12:00 pm

bwaz wrote: busdaddy wrote: There's just 1 looong wire that is gounded to the top at one end, goes all the way to the bottom and comes back up the other side where it attaches to the gauge terminal, the float moves a contact that bridges the wire and changes the resistance. Here's type 3 one, different length but same principle:

And what goes wrong on these type units? The wire, or are their some brushes that contact on the shaft?

http://www.thesamba.com/vw/forum/viewtopic.php?t=611056&highlight=

see this link.

Fri May 01, 2015 1:10 pm

Hmmmmm....I think that one is built differently from the almost identical cylinder type gauges on my 412. Let me open one tonight and see.

The first one I remember opening....long ago....had a center rod of what looked like bakelite plastic. It was a three sided or four sided rod with wire wrapped around it in a spiral with odd spacings here and there to change the resistance to match the variations of the tank shape at any given level (I speculate).

I will see if I still have that one or one like it. Ray

Fri May 01, 2015 1:49 pm

raygreenwood wrote: Hmmmmm....I think that one is built differently from the almost identical cylinder type gauges on my 412. Let me open one tonight and see.

The first one I remember opening....long ago....had a center rod of what looked like bakelite plastic. It was a three sided or four sided rod with wire wrapped around it in a spiral with odd spacings here and there to change the resistance to match the variations of the tank shape at any given level (I speculate).

I will see if I still have that one or one like it. Ray
Sounds complicated.
The bus one is just a single wire that goes down to the bottom and back up the other side and grounds to the lid, the float has a bridge contact that effectively shortens the wire as it rises changing the resistance.
The insulated rivet where the gauge connection passes through the lid also secures the spring plate the ground end of the wire is attached to and when it corrodes under there the sender stops.
Check out that thread WCFVW linked.

Wed May 23, 2018 10:24 am

Daverham!!! Hows the sender working?

Wed Jun 27, 2018 12:13 pm

Sorry if I'm bumping an old thread, but this how to is so great, it kind of deserves it.
Thanks a LOT for making this How-To. My fuel sender is now alive again!

While I was repairing my fuel sender, I made a couple of videos about it, in my Youtube channel named ecobus.

Here's the videos.

Fri Jul 17, 2020 7:34 pm

Thanks OP. Just ordered the wire and will take a crack at fixing my OEM sender. Seems the Chinese senders are barely better than my broken sender.
The coiled wire and moving contact reminds me of my younger days taking Scalextric model car racing handles apart, looks a similar principle. :)

Sat Aug 01, 2020 7:14 pm

wagohn wrote: Thanks OP. Just ordered the wire and will take a crack at fixing my OEM sender. Seems the Chinese senders are barely better than my broken sender.
The coiled wire and moving contact reminds me of my younger days taking Scalextric model car racing handles apart, looks a similar principle. :)

Thanks OP. I gave it my all but no go. I created my "hole" pretty much directly over the sender and things were looking good. However, looks like the PO had already replaced the original sender with a VDO version. I tried to fix the VDO version, as I know they are decent, but had issues as follows.
Though I was able to wind the wire successfully, and when touching one end of the wire and various points on the coil board, I was getting between 5 and 70 ohm. Great! Then the problem. No matter what I did, when I tried to get a reading using the swing arm, I got nothing on my meter.
Played around with it for hours but no joy. Works when directly testing the coil, nothing when the arm is back on - I adjusted the contact a bunch of times but same issue.
So, I ordered a $35 JBUG sender. I know they're not great but I have nothing at the moment. The seal on the VDO sender was shot anyways.
Thanks :)

Wed Aug 05, 2020 11:54 am

wagohn wrote: wagohn wrote: Thanks OP. Just ordered the wire and will take a crack at fixing my OEM sender. Seems the Chinese senders are barely better than my broken sender.
The coiled wire and moving contact reminds me of my younger days taking Scalextric model car racing handles apart, looks a similar principle. :)

Thanks OP. I gave it my all but no go. I created my "hole" pretty much directly over the sender and things were looking good. However, looks like the PO had already replaced the original sender with a VDO version. I tried to fix the VDO version, as I know they are decent, but had issues as follows.
Though I was able to wind the wire successfully, and when touching one end of the wire and various points on the coil board, I was getting between 5 and 70 ohm. Great! Then the problem. No matter what I did, when I tried to get a reading using the swing arm, I got nothing on my meter.
Played around with it for hours but no joy. Works when directly testing the coil, nothing when the arm is back on - I adjusted the contact a bunch of times but same issue.
So, I ordered a $35 JBUG sender. I know they're not great but I have nothing at the moment. The seal on the VDO sender was shot anyways.
Thanks :)

It seems you're already sorted with the new sender, but if you still want to have a go at fixing the OEM one, I'd suggest cleaning up the contact surface where the swing arm meets the enclosure. They are often corroded and provide no ground return. Generally the multimeter reads infinite resistance in this failure mode.

Wed Aug 05, 2020 12:50 pm

furgo wrote:
It seems you're already sorted with the new sender, but if you still want to have a go at fixing the OEM one, I'd suggest cleaning up the contact surface where the swing arm meets the enclosure. They are often corroded and provide no ground return. Generally the multimeter reads infinite resistance in this failure mode.

Thanks, I tried that too. If I had to guess, it could be the windings are touching at some place when the unit is reassembled.
I've kept all my pieces, have a bunch of spare wire, so may try from scratch at a later date when this Chinese knock-off inevitably fails. :)

Either way, thanks to the OP for the learning experience.

Fri Dec 03, 2021 8:22 am

Has anyone tried this sender repair using 34AWG wire?

In the photos it seems like the winding of the repaired senders using 36AWG wire are quite a bit more loosely spaced than the original sender windings.

Mon Apr 10, 2023 7:24 pm

Sorry to resurrect an old thread but it is so valuable and thanks to the OP for the tutorial! The last post does pose an unanswered question that I will answer. Yes, somebody has tried 34 gauge wire and from what I can see it works better than the 36. 70 ohms resistance of wire fits nicely on the board.

Also to address another question about soldering: In my unit the nichrome wire attaches directly to the connection post (no insulated copper wire between). With the nichrome wire wrapped around the post a glob of solder holds it there even though it may not be technically "soldered" to the post. To secure the wires on the board I mixed a teaspoonful of polyester resin with 3 drops of hardener to coat the edges and rear side of the board.

And I'll reiterate what's been said many times- clean up your wire connectors! A little steel wool works wonders.

Before:

After: