1962 Gas Gauge Puzzle

[Jack H.]

Re: 1962 Gas Gauge Puzzle

If you're going to run a temporary ground for test purposes, going directly to the battery Neg post is preferred. Why?

You need to insure you have a good 'bite' when grounding to the chassis. Things like paint & oxidation can cloud the issue, that's unless you want to drill a fresh hole in the chassis + use a clean/new screw and washer...

Personally, I'd wait on the outcome of your temporary test that routes directly to the battery negative terminal!

[Bill O.]

Re: 1962 Gas Gauge Puzzle

John, Roy and Jack,

STATUS OF TESTS

• I misspoke when I reported that with less than 1/4 tank, gauge works with cold motor....after sitting overnight, she showed earlier symptoms
• Brown wire removed from sending unit shows 12 volts with ignition on.
• Brown wire removed from sending unit, ignition on, needle shows "FULL"...connections cleaned and wire reinstalled.
• Ground wire from tank to each of the four ground lines at tail lights shown zero OHMS of resistance.
• Extra ground line from sending unit to NEG BAT....ignition on, gas gauge working properly...but needle still reacts some to signals on and brake depressed????...but not as much as without this extra ground.
• Get This..Extra ground wire removed, ignition on, cold motor, sitting overnight, gauge works perfectly???

I must be missing something??????
Thanks much for all the help. I think I should install the extra ground at a minimum.

[John W.]

Re: 1962 Gas Gauge Puzzle

The easy fix would be to run the extra ground wire if you can conceal it well enough.

But there is still an underlying problem. It could be your battery ground to the chassis is weak. It could be the ground from your tail light assembly is weak. Circuits like this can drive you nuts. On a 46 year old car probably all of the ground connections are weaker than they could be. It could also be affected by broken stands within the stranded wire.

The Ohm meter tells you that the wire can carry 9 volts and no current without any resistance. That same wire will have resistance when you run 13.7 volts and a fair amount of current through it. Your gas gauge and your amp meter are probably the only two things that would see this level of resistance as a problem. Your lamp bulbs are a couple candlepower short of full on, but you would need a pretty good light meter to see that difference.

When you have spare time just undo and clean each ground connection that you can find. A little Copper based Never Seez will really help those connections. Copper Never Seez is used by the boiler industry and others as a pipe sealant and never seez. I have used it for years for electrical contact lubricant and conductivity enhancement. I use it on my battery connections to resist corrosion, I use it on all kinds of wire connectors. Use a toothpick to apply it to the spade lugs before you plug them in to the female terminal. Keeps moisture and corrosion out.

Be careful not to get it across terminals of different circuits, it will short them out.

You can find it here https://neverseezproductscart.secure...rns10br1-oz&os for less than $5.00 for a 1 oz tube. Only $9.60 shipping.

If you live near a big city you may find this available at a plumbing supply store without the shipping cost. May not find the 1 oz tube though.

I would say that it is easily worth the $15.00 for the agravation that it can save.

[Bill O.]

Re: 1962 Gas Gauge Puzzle

Final
Prepared a permanent second ground wire from the sending unit following the gas line down and along chassis to first gas line clamp. Fastened the new ground out of sight behind the clamp (Christopher Ritche's idea from last March). Now, ignition on, cold motor, gauge reads perfectly and doesn't budge with signal or brake lights on!!

Thanks to all for valuable advise.