TheSamba.com Forums
 
  View original topic: Another fuel sender repair method T2a Page: Previous  1, 2, 3, 4
CerveloMikey Thu Nov 16, 2017 11:25 pm

Here it is disassembled. Looks like the wire to the lug broke. Simple soldier job to repair it. Do I need to use special wire or will anything work?




busdaddy Fri Nov 17, 2017 8:03 am

Little tiny winches to tension the hair wire, how cool is that!? They don't make stuff like that anymore. 8)

Yes regular copper wire will do that job fine.

TomWesty Mon Feb 05, 2018 4:00 pm

busdaddy wrote: Little tiny winches to tension the hair wire, how cool is that!? They don't make stuff like that anymore. 8)

Yes regular copper wire will do that job fine. Yeah, thatís cool. Tension it with the winch and lock it down with the set screw.

SGKent Mon Feb 05, 2018 4:32 pm

TomWesty wrote: busdaddy wrote: Little tiny winches to tension the hair wire, how cool is that!? They don't make stuff like that anymore. 8)

Yes regular copper wire will do that job fine. Yeah, thatís cool. Tension it with the winch and lock it down with the set screw.

y'all should have been around when we went from stones to copper.... the iron guys who came along behind us didn't have a clue how that stuff worked......

sodbuster Mon Feb 12, 2018 9:50 am

I'm in the process of going through my bus after it's engine gave up the ghost. Along with the rebuild one of the things on the "while I'm in there" list is to get my fuel gauge working again. It has always kind of worked but not too well. whenever I would fill up the gauge would read either full or a little over 3/4 of a tank. It would function ok at first, then the needle would just dive to empty with the tank at least 3/4 full.

So "while I was in there" I pulled my fuel tank to get at the sending unit. With sending unit in hand I started checking the sender out using Telfods exelent repair notes. It tested good. 3.3 ohms full 78.4 ohms empty It's testing good. Give it a bit of a shake a few light taps nothing is fazing the reading on the meter. It's solid.

I was a little confused to discover this. The sending unit seemed fine. So I forged ahead and checked the gauge. When the sending unit wire was grounded the needle on the gauge would not go much past 3/4. Now I am questioning the gauge instead of the sending unit at this point. So I decide to put it down for awhile and work on some thing else.

I ventured to have another look last night and wouldn't you know, the sending unit has now gone jankey on me and is now clearly testing bad. Upon further inspection I deemed it a prime cannadate for Telfords repair method which I will do. (I also have another I can fix as well.) But it is the guage itself that has me tapping the keys today.

Unlike the later models that have a "vibrator" included on the fuel gauge circut to drop voltage to the gauge. The early bays do not have this component. The Bently shows two wires to the fuel gauge on my '71 bus. One from the sending unit and another from the #15 terminal on the fuse block. This is a strait 12 volt tap through the ignition switch. (key'd hot.) There is nothing before the gauge to drop voltage to it. So either it is not required or is internal to the gauge I don't know which.

So here is where I am at with this. I need to effect a repair of the sending unit. Hopefully that will stop the guage from suddenly dropping off to empty. But what to do about the gauge not going all the way to full? Obviously a voltage check of the #15 wire to the gauge is in order as well as checking and cleaning any grounds I come across under the dash. if the voltage test to the guage is good what else short of replacing the gauge outright need to be checked beyond what I have already listed?

telford dorr Mon Feb 12, 2018 9:59 am

Your tests are correct. Open circuit at the sender should read empty. Short to ground should read full. Check all of the connections in the sender circuit (including the fuse).

Early Bays have no voltage regulator. 12 volts direct to the indicator. Indicator to sender. Sender to ground.

Senders tend to either work or not work. As a sanity check, check your meter probes. Sometimes it helps to take a ScotchBrite pad to the probe tips, which get oxidized over time and give you bad readings. Short the tips together and verify that you read less than 1 ohm.

sodbuster Mon Feb 12, 2018 10:50 am

telford dorr wrote: Your tests are correct. Open circuit at the sender should read empty. Short to ground should read full. Check all of the connections in the sender circuit (including the fuse).

Early Bays have no voltage regulator. 12 volts direct to the indicator. Indicator to sender. Sender to ground.

Senders tend to either work or not work. As a sanity check, check your meter probes. Sometimes it helps to take a ScotchBrite pad to the probe tips, which get oxidized over time and give you bad readings. Short the tips together and verify that you read less than 1 ohm.

Thanks for the confermation Telford. Looks like a voltage drop test is what is next up in the process. Just to see if the gauge is getting everything it needs.

busdaddy Mon Feb 12, 2018 11:10 am

sodbuster wrote: But what to do about the gauge not going all the way to full? Obviously a voltage check of the #15 wire to the gauge is in order as well as checking and cleaning any grounds I come across under the dash. if the voltage test to the guage is good what else short of replacing the gauge outright need to be checked beyond what I have already listed?
Mine did that for years until it finally died last year (the almost full thing, mine didn't drop randomly), after repairing the sender ground and soldering the G wire side of the circuit on both the wet and top side of the rivet it now reads full like one would expect it to. It's not just the ground connection that gets weak.
Soldering the G side is a little tricky, linger too long with the iron and you'll melt the plastic ferrule it goes through, you can rehammer the rivet to tighten it up, but bucking it in a vice and holding it as you hammer requires maximum pucker, that hair wire is always in the danger zone. An alternate fix would be run a second wire through the lid for the G and seal it just like the ground.

sodbuster Tue Feb 13, 2018 2:46 pm

busdaddy wrote: sodbuster wrote: But what to do about the gauge not going all the way to full? Obviously a voltage check of the #15 wire to the gauge is in order as well as checking and cleaning any grounds I come across under the dash. if the voltage test to the guage is good what else short of replacing the gauge outright need to be checked beyond what I have already listed?
Mine did that for years until it finally died last year (the almost full thing, mine didn't drop randomly), after repairing the sender ground and soldering the G wire side of the circuit on both the wet and top side of the rivet it now reads full like one would expect it to. It's not just the ground connection that gets weak.
Soldering the G side is a little tricky, linger too long with the iron and you'll melt the plastic ferrule it goes through, you can rehammer the rivet to tighten it up, but bucking it in a vice and holding it as you hammer requires maximum pucker, that hair wire is always in the danger zone. An alternate fix would be run a second wire through the lid for the G and seal it just like the ground.

Looks like the path of least resistince at this point. I'm gonna let that sleeping dog of a gauge lay. Though I did take my sending unit in with me to work where I have access to better quality soldering tools and equipment.
I'll instal it and put the tank back in when I get home today. :D


By the way. That final OHM test to check the repair was sweet sweet victory. :wink:

sloans265 Mon Aug 20, 2018 9:05 pm

So I rebuilt my sending unit but it appears I still have a problem with it(?) Empty the sender is reading @ 75 resistance and 2.8 resistance FULL. However when I hooked it up to the gauge for testing the gauge went straight to FULL.
I got another ďtestedĒ gauge and still same result Gauge says full when sender is at empty. HOWEVER when you move float on sender up to full you can see needle just barely move up itself..
For what itís worth I did hook it up to a beetle speedo/fuel gauge I had laying around and that gauge did respond.
Is there something Iím overlooking? The performed the only ďtestĒ I found for the gauge and it passed. Iím not going through harness, Iím using gauge/sender/battery
Thanks for any help!



Powered by phpBB © 2001, 2005 phpBB Group