66 Fuel Gauge Issues - Chevelle Tech
Electrical & Wiring Troubleshooting electrical problems.

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post #1 of 16 (permalink) Old Aug 5th, 17, 2:23 PM Thread Starter
 
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66 Fuel Gauge Issues

Alright, so I'm a bit confused as of now. I'm new to the forums and I own a 66 Elcamino (sorry if its not a Chevelle its close enough hopefully) and I'm having fuel gauge issues. I recently rewired my whole vehicle as I had brake light issues and it was a mess anyways... So i spent the last 2 months rewiring it on the weekends. Ive finished it up and everything works as expected except for the fuel gauge, its stuck past full. I've checked the voltage from the power wire to the gauge and its getting 12v and my sending wire is reading at 81 ohms (yes it works, before it read 53 and i filled it up and went on a drive). So i'm confused as of why its reading full and doesn't change at all.
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post #2 of 16 (permalink) Old Aug 5th, 17, 3:51 PM
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Brian
 
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Sounds like a ground issue to me. Had the same issue with stuck past full. If you ground the wire that comes to the sending unit in the tank the gauge will drop to empty if it works correctly.
That was my first issue...after getting the gauge to respond and cleaning my ground I then discovered that my sending unit was corroded and stuck...has to drop the tank and put a new one in.
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post #3 of 16 (permalink) Old Aug 5th, 17, 4:16 PM
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Bill
 
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Re: 66 Fuel Gauge Issues

I'm going for a ground issue also. And, yes, we love El Caminos here. Got pictures? And, Welcome to the site!
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post #4 of 16 (permalink) Old Aug 5th, 17, 8:21 PM Thread Starter
 
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Re: 66 Fuel Gauge Issues

Thank you for the response, I tried the grounding method and it worked to an extent, it dropped from full to almost empty. It didn't go all the way to empty, more or less a bit below a 1/4 tank. Could that be an issue?
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post #5 of 16 (permalink) Old Aug 5th, 17, 8:21 PM Thread Starter
 
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Re: 66 Fuel Gauge Issues

Thank you!
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post #6 of 16 (permalink) Old Aug 5th, 17, 9:28 PM
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Re: 66 Fuel Gauge Issues

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Originally Posted by 66RADMINO View Post
Thank you for the response, I tried the grounding method and it worked to an extent, it dropped from full to almost empty. It didn't go all the way to empty, more or less a bit below a 1/4 tank. Could that be an issue?
Good deal...from what I learned and in my case that meant the actual gauge in the dash and your wire that goes from the sending unit to the gauge are good.
There should be another wire that comes off the sending unit that goes to the floor pan or frame to ground it. Make sure the spot it is connected to is clean. I got no response when I cleaned that up...also took a piece of wire and ran a jumper from it to a clean bolt on the frame and still got no response...which meant it was my actual sending unit. Was hoping to avoid pulling the tank...but did not. Was actually easy in the Chevelle, not sure about how it is on the Camino. Might check to see if there are bad splices in the ground wire too...mine had 2 splices...replaced it with a clean wire.

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post #7 of 16 (permalink) Old Aug 6th, 17, 5:32 AM
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Re: 66 Fuel Gauge Issues

Tank full = 90 ohms
Tank empty= 0 ohms

And in between.

The ohm reading should be taken between the sender wire [ temporarily ] removed from the gauge & ground.
Also make sure there is a ground connection between the body & the block or bat -ve terminal. Ground straps can vary between models.
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post #8 of 16 (permalink) Old Aug 6th, 17, 7:42 AM
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Re: 66 Fuel Gauge Issues

Did the fuel gauge work before the rewire? Either way, it is down to the sender or the sender (and tank itself) being grounded.

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post #9 of 16 (permalink) Old Aug 6th, 17, 1:36 PM Thread Starter
 
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Re: 66 Fuel Gauge Issues

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Originally Posted by Pioneer4x4 View Post
Did the fuel gauge work before the rewire? Either way, it is down to the sender or the sender (and tank itself) being grounded.
Yes the fuel gauge had worked before the rewire.
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post #10 of 16 (permalink) Old Aug 6th, 17, 2:07 PM Thread Starter
 
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Re: 66 Fuel Gauge Issues

Alright so today I checked the ground wire from the sending unit to the frame and cleaned it up and made a new ground. Still doesn't work, wants to stay past full and my sending wire is reading 90 ohms to the gauge so it should be on full. I'm guessing its the sending unit itself, but just a month ago the sending unit was working fine and no issues at all, and its reading off an ohm rating that is correct and should be where its at as I just filled it up a day ago and it read 103 ohms at the gas station and I drove for 30 min back home and it read at about 90 ohms. Any other suggestions?
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post #11 of 16 (permalink) Old Aug 6th, 17, 7:28 PM
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Re: 66 Fuel Gauge Issues

Could be stuck if you can wack on the tank near the unit it might free up who know worth a try.

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post #12 of 16 (permalink) Old Aug 6th, 17, 9:17 PM
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Re: 66 Fuel Gauge Issues

This is how I fixed the one on my old truck, I thought it might be similar to your El Camino . I had to replace the resistor on the back of the fuel gauge. My old one showed a open lead. I bought the replacement on ebay.
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post #13 of 16 (permalink) Old Aug 6th, 17, 10:08 PM Thread Starter
 
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Re: 66 Fuel Gauge Issues

Alright, so I found an interesting theory. So i drove it today and when i floored it the gauge began to move. So I got home and let air out of my air shocks and the gauge moved down. Since the sending unit is in the front of the tank and I have the rear end raised could the gas being pooled up towards the front of the tank be the issue? Haven't done much other testing since I had other priorities.
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post #14 of 16 (permalink) Old Aug 7th, 17, 5:58 AM
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Re: 66 Fuel Gauge Issues

Use a jumper to ground the sender terminal on the back of the gauge. Gauge should read empty.
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post #15 of 16 (permalink) Old Aug 7th, 17, 6:58 AM
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Re: 66 Fuel Gauge Issues

You have probably done this already but check the resistance from the sender terminal to the sender housing, then from the sender terminal to the frame. The readings should be the same, this checks you ground path.
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