Topic: Gas guage


silverchief    -- 08-07-2016 @ 5:30 PM
  In my 46, the gas gauge moves to the gallons available
position when you turn the key on, and to the empty position when you turn the key off - as it is supposed to operate.

However, recently it started refusing
to drop off the full marker with the key on,when
I know I have used at least 8 gallons of gasoline.

One wire from the tank device goes to the fuel gauge and the other to the ignition switch.

Is the trouble most lkely in the cork/wire device in the tank,or in the wiring?

A complete wiring harness was installed several months ago, and all in dash gauges were pulled and cleaned up at the time. No problems.

Where should I start checking?



trjford8    -- 08-07-2016 @ 5:52 PM
  First make sure the tank has a good ground. In the 46-48 cars grounding is a real issue. Make sure the wire to the sending unit is tight and the contact clean. Then run an extra ground wire from one of the screws on the sending unit to a good clean ground on the frame. Also check to make sure the two wires on the gauge are nice and tight. If this does not solve the problem get back to us.


deluxe40    -- 08-07-2016 @ 7:34 PM
  In your question you say: "One wire from the tank device goes to the fuel gauge and the other to the ignition switch."

When I look at the schematic I see one wire from the fuel gauge to the "tank device" (sending unit) and another from the sending unit to ground. That's how all of the units I have owned were wired. Is that a typo in your question or does it reflect your recent wiring? The wire from the ignition switch usually goes to the other pole on the gauge (via a buss to the other gauges). See vanpeltsales.com for wiring diagrams and schematics.


silverchief    -- 08-08-2016 @ 10:03 AM
  You are right delux40, a second close look at the schematic shows one to the dash gauge and one to ground.

I am going to start going through the suggestions and will get back.


TomO    -- 08-08-2016 @ 4:44 PM
  Bill, the gas gauge reads full when you ground the wire to the sending unit. My guess is that the access cover for the sending unit is contacting the screw that holds the wire to the sending unit. Put a couple of layers of Gorilla tape on the cover where the screw is.

Tom


silverchief    -- 08-08-2016 @ 8:29 PM
  Tom,

When I uncovered the sending unit, it had the correct new wire coming from the dash gauge and attached to the center post.
No other wires or connections were present.

As suggested, I ran a wire from one of the screws holding the sending unit in place, to a nearby good clean ground.

I then filled the tank which took 6 gallons, even though the gauge read full. I will put a tape barrier as you suggested between the center post and the lid. As little as I drive the car it will take about three weeks to see if the needle will drop off the full mark. I will then check back in.
Thanks for all suggestions.






Drbrown    -- 08-08-2016 @ 8:55 PM
  All I can add to this discussion is that the arm on your sending unit may be getting stuck. Sometimes when I fill or partially fill my '47, the gauge indicator does not rise to the proper position. If I bounce on my rear bumper it will then rise to the proper reading. Also, I notice that after re-starting after adding gas, it sometimes takes a minutes for the heating coil in the gauge to "catch-up" with the new reading from the sending unit.


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