67 Coronet 440 fuel gauge not working

[DAH]

I am looking for help to get my fuel gauge working. My car is all original with less than 58,000 actual miles. I installed a new float when I had to replace the gas tank. I was hoping the dash gauge would start working but it is still showing empty. The dash lights are also very dim. Wondering if the two are related.

Any help to solve this problem would be appreciated.

 

[JimCoronette]

Dash lights and gauges are not related.

1. Was the ground strap put back on the sending unit after the float was replaced?
   
2. Was the sending unit replaced with the float?
3. Is the temperature gauge working?

 

[66383]

Can't stress GOOD grounds enough!

 

[miller]

I am looking for help to get my fuel gauge working.

Okay...a little long-winded, so hang on. Don't matter, but what year car?

First, do NOT replace the fuel sending unit, if it's original. As long as it's not a rusted hulk, it can be made to work. Pretty much all the after-market units are junk.
You could easily be looking at bad wires. Need to test everything, to figure out why it's not working. The fuel gauge on my 64 works great. Yeah, I had to test all, too.

You need an ohm meter, 3 'D' batteries, and a few test leads (wires).

Check the gauge itself, first. Dis-connect the car's battery, and pull the instrument panel. Look over the backside of the panel, while your at it. You'll want to dis-connect all the wiring from the panel.
To test the gauge, keep in mind it works off of 5 volts. That's what the voltage reducer does, supply 5 volts to the gauge. Connect the 3 'D' batteries together, with test leads going to the two posts on the gauge itself. If the gauge is good, it will 'slowly' move from empty to full, making the complete sweep. If it doesn't, the gauge is bad. If you hook 12 volts to the gauge, it will burn out, so don't!

Use the ohm meter, to test the wiring for the gauge. From end to end, + wire at the gauge, to the sending unit wire, at the tank. If it has more than 1 ohm resistance, probably need to look at each connector, and check each 'segment' of the wire, going from gauge to tank. (Mine was .4, and works fine.)

I won't get into testing the sending unit, for now. Plenty of info on how to test them. But, you do need to check for good grounds, both at the instrument panel to the car body, and the sending unit/steel fuel lines.

 

[DAH]

The car is a 67. I ran the car for 20 minutes and the temp gauge did register (see photo).

 

[DAH]

First, thank all of you for the help. I will try to answer everyone's questions. The car is a 67. I ran the car for 20 minutes and the temp gauge did register (see photo). I replaced the whole sending unit not just the float. The grounding strap was reconnected to the new sending unit. I am not sure if I still have the original sending unit. It may still be in my garage.

 

[69L48Z27]

Pull the wire from the sender and ground it. If gauge goes to full then your wire to the front of the car and gauge are working. You’ll figure out quick which end of the car you need to work on.

Based on the temp gauge working you ‘should’ have voltage at the gauge.

 

[1 Wild R/T]

Pull the wire from the sender and ground it. If gauge goes to full then your wire to the front of the car and gauge are working. You’ll figure out quick which end of the car you need to work on.

Based on the temp gauge working you ‘should’ have voltage at the gauge.

I agree, but will add don’t leave the key on for long, watch the gauge sweep full travel then turn the key off.. The spec for the sender is 10-73 Ohms... when you ground the sender wire your providing zero ohms and I have seen gauges damaged by leaving the power on for to long...

 

[DAH]

If I ground the wire from the sender it won't be harmful until the key is turned on?

 

[1 Wild R/T]

Nope... And even then you have a little time, a minute is likely fine, five minutes & you might let the magic smoke out...

 

[69L48Z27]

You’ll be fine. Also, if your ground circuit is great you’ll still have like 2 ohms resistance through the body.

Crawl under the car and put a grounding lead on the sender wire. Jump up go click the key on and see what happens. Watch the gauge climb up. Click the key off and crawl back under the car and disconnect. Shouldn’t take more than 90 seconds. All your trying to do is prove out which end has the problem.

If you have a helper have them do the stuff up top. If you’re still concerned go to Radio Shack and get a 10 ohm resistor. Oh wait... Radio Shack. Never mind.

 

[1 Wild R/T]

You’ll be fine. Also, if your ground circuit is great you’ll still have like 2 ohms resistance through the body.

Crawl under the car and put a grounding lead on the sender wire. Jump up go click the key on and see what happens. Watch the gauge climb up. Click the key off and crawl back under the car and disconnect. Shouldn’t take more than 90 seconds. All your trying to do is prove out which end has the problem.

If you have a helper have them do the stuff up top. If you’re still concerned go to Radio Shack and get a 10 ohm resistor. Oh wait... Radio Shack. Never mind.

Agreed on all points!!

 

[DAH]

I am much older than the car so I don't crawl under anything anymore I have a lift in my garage so that I don't have to crawl under cars anymore! I asked because I will need to lower the car after grounding the sending wire to turn on the key.

Thanks for the responses guys. You all are the best.

 

[miller]

I replaced the whole sending unit not just the float.

You might get lucky, and have one that kinda works.
Difference between the OEM unit, and after-market, is the windings in the after-market.
I bought one for mine...it's still in the box, never to be used. Pure junk, the way it's made. Cleaned up my OEM, and put it to work.

Most of the time, it will be something fairly simple, that keeps the fuel gauge from working. Just have to hunt it down. Good luck.

 

[miller]

Don't matter, but what year car?

Duh! Too early in the morning, I guess.

 

[DAH]

If I can't find my original sending unit, is there anyplace to get a good one? Wish I had known this when I was changing the tank.

 

[69L48Z27]

Good aftermarket? Nope. You’ll have to play with the float arm, tweak it, to get it close. If not it’ll never read full.