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Sun Jun 02, 2019 4:40 am

Hi All. The fuel gauge on my 1967 Ghia is not registering correctly. Although I have a full tank of gas, it only reads half full. It is a new sending unit and appears to be correctly wired. I put a voltmeter on it and I do get a pulsing read out. It jumps around between 1 to 3 volts when the car is NOT running, but has the ignition turned on. I have a 1967 VW service manual, but it has no information on this. It only says that in 1967 "Karmann-Ghias have an electric fuel gauge" and not the mechanical one. Any help is greatly appreciated (though I know it's only important to know when you are almost out of gas and that I can always pop the trunk and look into the gas tank for a read.
Thanks!

Sun Jun 02, 2019 6:08 am

take the wire off of the sending unit. With the key switched to 'on' the gauge should go all the way one way. Short the sending unit wire to a good ground, the gauge should go all the way the other way. If it does, your sending unit is bad.

Sun Jun 02, 2019 6:26 am

OR it could be a wrong sending unit for the gauge.

Sun Jun 02, 2019 8:02 am

Thank you for the help! I did the test runamoc suggested and when disconnected it registered empty; when shorted it registered full. That indicates either a defective sending unit or a wrong sending unit, essentially the same result in that I need to purchase a new component. Funny thing is, this was just restored in March and it is a shiny, brand new sending unit. Is it possible that it is a aftermarket electrical sending unit for a 6v Ghia? Would that explain why it only reads to half full? More mysterious, I seem to remember that i did read full at one time and only recently started this half-full routine. False memory? It seems unlikely that a new unit would go bad so quickly. Anyway, I need to just buy a new unit and move on to why the turn signal indicator lights don't work (although the blinkers blink just fine) and maybe get the clock going. Thanks again for the advice, but do you agree that I need to purchase a new sending unit despite it being only a few months old?
Mike (mguilfoile)

Sun Jun 02, 2019 8:25 am

Before you go and spend your money on a new sender that might also fail.... have a look in the sticky where we gather the best “how to” threads. ... here...
https://www.thesamba.com/vw/forum/viewtopic.php?t=433752
There are two threads listed on the topic of fuel senders if you scroll down to the “instruments” sub heading. Try looking there and see if that leads you to the failure mechanism.

Nicholas

Sun Jun 02, 2019 8:31 am

Quote: do you agree that I need to purchase a new sending unit

Once you get the old sending unit out test it by connecting the base to ground with a jumper wire or something. Then connect the sending unit wire back up to the center of the sending unit. With the key switch on, of course, move the float around and see what the gauge reads. Then you'll have a better Idea if you need a new one.

Mon Jun 03, 2019 4:00 am

Thanks to everyone! Great advise. Next weekend I'll dig into this...and a few other electrical and mechanical problems.

Tue Jun 04, 2019 5:50 am

mguilfoile wrote: Thank you for the help! I did the test runamoc suggested and when disconnected it registered empty; when shorted it registered full. That indicates either a defective sending unit or a wrong sending unit, essentially the same result in that I need to purchase a new component. Funny thing is, this was just restored in March and it is a shiny, brand new sending unit. Is it possible that it is a aftermarket electrical sending unit for a 6v Ghia? Would that explain why it only reads to half full? More mysterious, I seem to remember that i did read full at one time and only recently started this half-full routine. False memory? It seems unlikely that a new unit would go bad so quickly. Anyway, I need to just buy a new unit and move on to why the turn signal indicator lights don't work (although the blinkers blink just fine) and maybe get the clock going. Thanks again for the advice, but do you agree that I need to purchase a new sending unit despite it being only a few months old?
Mike (mguilfoile)
Seeing as you are having electrical issues with more than one circuit, I would suggest that you take the time to clean up all of the electrical Ground connections and make absolutey certain that proper contact is being made and maintained.
Once you've finished cleaniing up the Ground connections, do likewise with the connections in the Fuse Box and see if perhaps everything is once again operating properly.

Tue Jun 04, 2019 6:18 am

KGCoupe wrote: mguilfoile wrote: Thank you for the help! I did the test runamoc suggested and when disconnected it registered empty; when shorted it registered full. That indicates either a defective sending unit or a wrong sending unit, essentially the same result in that I need to purchase a new component. Funny thing is, this was just restored in March and it is a shiny, brand new sending unit. Is it possible that it is a aftermarket electrical sending unit for a 6v Ghia? Would that explain why it only reads to half full? More mysterious, I seem to remember that i did read full at one time and only recently started this half-full routine. False memory? It seems unlikely that a new unit would go bad so quickly. Anyway, I need to just buy a new unit and move on to why the turn signal indicator lights don't work (although the blinkers blink just fine) and maybe get the clock going. Thanks again for the advice, but do you agree that I need to purchase a new sending unit despite it being only a few months old?
Mike (mguilfoile)
Seeing as you are having electrical issues with more than one circuit, I would suggest that you take the time to clean up all of the electrical Ground connections and make absolutey certain that proper contact is being made and maintained.
Once you've finished cleaniing up the Ground connections, do likewise with the connections in the Fuse Box and see if perhaps everything is once again operating properly.
You forgot to tell him to give everything a good slathering of dielectric grease.

Tue Jun 04, 2019 6:23 am

iowegian wrote: [/quote You forgot to tell him to give everything a good slathering of dielectric grease.

Iowegian, since I am just now installing my new wiring harness, do you recommend I slap some dialectic across the connectors at the fuse panel once I have everything in place? How about around the connectors to the relays?
Jeff

Tue Jun 04, 2019 8:06 am

rbsurfguy wrote: iowegian wrote: [/quote You forgot to tell him to give everything a good slathering of dielectric grease.

Iowegian, since I am just now installing my new wiring harness, do you recommend I slap some dialectic across the connectors at the fuse panel once I have everything in place? How about around the connectors to the relays?
Jeff
Quite honestly, I have never used the stuff. But some regular contributors to theSamba swear by it and mention it frequently.

Tue Jun 04, 2019 9:52 am

iowegian wrote:
Quite honestly, I have never used the stuff. But some regular contributors to theSamba swear by it and mention it frequently.

There's even a debate as to the properties of dielectric grease...does it conduct or does it insulate? I kid you not, he said opening a fresh can of worms... https://www.w8ji.com/dielectric_grease_vs_conductive_grease.htm

Tue Jun 04, 2019 10:08 am

UGH, yes John, unfortunately that is what I always dread when asking a question, it usually ends up in a multiple page debate with so many answers I can never figure out which direction to go. I went through that with my Bergmann engine, and then the multiple pages on the repro Ghia bumpers from Vietnam. Let's not get started on the "what type of engine oil should I use" topic!!!!
Thanks, Jeff

Tue Jun 04, 2019 11:37 am

These fit/work. 8)
https://www.thesamba.com/vw/classifieds/detail.php?id=2281076

Tue Jun 04, 2019 4:34 pm

Quote: does it conduct or does it insulate?

if you don't use the thin brass, that turns black from corrosion, wire end connectors you wouldn't even need to use that stuff. :wink:

Tue Jun 04, 2019 6:30 pm

runamoc wrote: Quote: does it conduct or does it insulate?

if you don't use the thin brass, that turns black from corrosion, wire end connectors you wouldn't even need to use that stuff. :wink:

So, since I, and probably most people, are replacing their wire loom, which have the stock like brass connectors, should we smear the dialectic grease over them or not? Or should we shrink tube the connectors and then plug them in?

Inquiring minds must know..........

Tue Jun 04, 2019 8:32 pm

rbsurfguy wrote: runamoc wrote: Quote: does it conduct or does it insulate?

if you don't use the thin brass, that turns black from corrosion, wire end connectors you wouldn't even need to use that stuff. :wink:

So, since I, and probably most people, are replacing their wire loom, which have the stock like brass connectors, should we smear the dialectic grease over them or not? Or should we shrink tube the connectors and then plug them in?

Inquiring minds must know..........

You can smear them with that if you want. Regular bearing grease will do the same thing. It will prevent the oxidation that will occur with the brass connectors.

Wed Jun 05, 2019 3:32 am

Noted, thank you Sir.

Wed Jun 05, 2019 4:54 am

Quote: dialectic

Based on some discussions, I'm puzzled as to what folks think this stuff is and what it does. Like with condensers/capacitors. They consist of two 'plates' separated by a dielectric substrate. :? Does this mean a dielectric is an insulator? Yes, it does or the capacitor wouldn't work.

To better understand this: From Wikipedia * A dielectric (or dielectric material) is an electrical insulator that can be polarized by an applied electric field*

https://en.wikipedia.org/wiki/Dielectric

On VW electrical wiring Dielectric Grease seems to be used to 'seal' an electrical connection. As I said, regular bearing grease would achieve the same desired result. It doesn't improve or take away from the actual mechanical connection between the two connectors. Like solder, it's used to hermetically seal a mechanical connection.

In other words, dielectric grease is being used to prevent corrosion of the brass connectors...only!

Wed Jun 05, 2019 6:02 am

runamoc wrote:

In other words, dielectric grease is being used to prevent corrosion of the brass connectors...only!
Thank you for a good explanation.