Replace '62 Fuel Gauge Sender?

[Joel Falk]

Hello all,

The fuel gauge on my '62 has never really worked. It always seems to between 1/4 and 1/2 tank. If I put a lot of gas in the car it might go just beyond 1/2 but quickly (within 15 minutes of driving) goes back down to it's usual place.

Well I finally got around to taking a look at things and now I'm not really sure where things stand. I removed the brwon wire from the sender and the gauge went to full, which is what I think should be happending. I grounded the brown wire and the gauge went to empty. Also a good sign, right?

I put a mulitmeter on the brown wire (+) and the black w/white wire (-) and read 18v. Probably not good, but my multimeter never really reads a steady amount on anything so I am not too concerned.

Next I removed the sender from the tank, cleaned it and the wires up, attached them both and moved the sender arm from empty to full and the gauge showed 'E' through around 3/4. This is better and I attributed it to my cleaning of the wire connections so I reattached the sender to the tank. I could not get a resistance reading at all of the the sender though.

As I was tightening the brown wire the car went from 1/4 tank with the wire touching the post but still a little loose to 1/8 with it fully tightened. I'm not sure what this means. As an FYI, it looked like I had a little more than 1/4 fuel in the tank but it is hard to tell from the small sender hole.

I took the car out for a 15 mile drive and the gauge was mostly steady but went from 1/8 to E in that time.

What does everyone think? Does this sound like a bad sender (or possibly the wrong sender since it won't go above 3/4)?

[Rob M.]

Re: Replace '62 Fuel Gauge Sender?

Sounds like you float is has a leak...

greetings,
Rob.

[Jack H.]

Re: Replace '62 Fuel Gauge Sender?

Could be the float is 'water logged', could be the float arm is bent, or could be the wrong sender in the tank. One way to tell, is, with a nearly empty tank, to insert a 'hook' (bent coat hanger) grab the arm and exercise it through its excursion range. You ought to see the fuel gauge swing, in lockstep, between empty and full.

If you have access to a known good tank sender, you can connect it external to the tank and move its swing arm through the float range and confirm the dash guage follows properly.

[John H.]

Re: Replace '62 Fuel Gauge Sender?

The disconnect/ground check of the brown wire says the gauge is reacting correctly, so the problem is most likely at the sender end, either with a poor ground or a bad sender. Since you can't manually exercise a C1 sender like you can with a C2, you'll need to remove it from the tank and check resistance across the two terminals while moving the float arm - it should show 0 ohms at the "empty" end of travel, and smoothly increase to around 33 ohms at the "full" end of travel. While you're in there, run a separate dedicated ground wire from the sender flange to the frame.

[Frank H.]

Re: Replace '62 Fuel Gauge Sender?

The winding in the sending unit are most likely full of dirt to give a accurate
reading,if you were to take it apart,as thats how they usually go bad or the carbon tipped contact expired.So you might want to look inside it,I messed with one till I opened it up and all the windings were worn thru and the float had noting to do with its readings.
Frank