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Ok new fuel gauge, new wiring, new sending unit, new solid state voltage regulator. Gauge doesn't work it always reads empty.
Here is what I've done so far. Oh and Temperature gauge works so the voltage limiter is OK.
Pulled the cluster and put a test light to the gauge. Get a low pulsing light, check. Grounded the guage out and it goes to full. Check, gauge is good, right?
put a second ground at the sending unit, still on E. Grounded the guage at the sending unit gauge goes to full so the wiring is ok from the gauge to the sender.
Pulled the the sending unit and it ohm tests ok on the bench. Hook it up in the trunk and manually move the float to full, gauge reads full. Move it to half, gauge reads half. Reads E in the E position.
Popped the float off put it in water and it floats no holes in it. Scratch my head and say it works.
Install it it back into the tank and it reads E ?????
oh and I just put 7 gallons in the tank that wasn't completly empty.
The sending unit isn't bent unless the old junker on my shelf is bent wrong in the exact same way. They match.
This is car hates me. Any ideas?
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The car doesn't hate you, you just have to show it some more love...or who's boss.
I'm wondering if the metal line or tank is not grounded to the frame. Start by taking an ohm reading with the sending unit in the tank. Don't keep taking things apart, do all tests with everything together.
Double check the wire and gauge by grounding the connector at the sending unit again. Then take an ohm reading between the sending unit to tank, then sending unit to the frame. If the sending unit is reading correctly, check to make sure you have the sending unit plug making a good connection.
You're almost there, just need a fresh look.
President, New England chapter of Coronetaholics anonomous.
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Thanks for the suggestions. I'll give them a try.
Posts: 114
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Joined: Apr 2014
Still stumped.
As suggested I grounded the sender at the tank. Gauge goes to full.
Then I ohmed the sender to its ground. It reads 60.6 which should be just under half a tank. But the gauge still says E.
grounded to the shock tower it reads 60.5. Which is splitting flea hairs.
The sender connection is good and clean.
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OK, take a close look at the connector between the wire and sending unit, it might not be making a good connection. Try squeezing it to make a tight connection.
You can also take an ohm reading at the kick panel to see what is happening. There is a connector at the kick panel on the drivers side. it should read about the same as the when you metered to the shock tower.
After that, I think you have a mystery Coronet.
President, New England chapter of Coronetaholics anonomous.
Posts: 114
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Thanks for the help. After my last post I went back to it.
No kick panel connection its wired direct to the gauge via a new Ron Francis harness. Connections are good.
I pulled it again and hooked it up in the trunk. Left the float in the F position for a while. It went to F but eventually rested on 3/4. Float in E position and the gauge finally rested way below E. I bent the float wire and got it so it reflected float position on the gauge better. Reinstalled and she stays on E(but not well below)
Pulled it it again and ohmed it on the bench. E is like 35 ohms, should be 10'ish. F is like 130, should 90'ish. I had to wait at least 3 minutes for the ohm meter to settle down no matter where I moved the float. Must be something screwy with the resistor in the sender.
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What year is your car? Using stock gauge and instruments?
I have a extensive write up on here for gas gauge repair.
Voltage limiter, Mother board havent been mentioned yet? If its still a stock setup? I could help ya get to the bottom of it.
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my bad. didnt read it to carefully.
Posts: 447
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Okay I read the poast again.
Ohm the sending unit body anywhere or around the lock ring to the tank, then to the body somewhere like the shock bolt on the leaf spring. both should measurments should be near 0 ohms. Meaning the tank and sending unit is grounded.
The gas gauge measures resistance to ground thru the stud on the sending unit. High resistance or a open circut cause the gauge to read empty or not at all. Zero resistance to ground will make the gauge read full.,
On my 67 I grounded the tank and the sending unit body via a small clamp on the 5/16 outlet of the sending unit and I used a small tiny balance weight clamp off the fuel tank flange and grounded that too.
check grounds. Then measure ohms from stud to ground with fuel in tank. Then ohm the gauge to tank wire to ground and they both should ohm the same within a few ohms.
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Once you get it working you might need to tweak the sending unit. Mine was from OER I got from classic industries. My sender had a adjustable float with a set screw on the sender shaft. I loosened mine and set it to the max and tightened up the set screw.
My gauge would read 3/4 on a full tank. Made the adjustment and it read full when its full.
Good luck
