Fuel Gauge Issue-78
Thread Starter
Le Mans Master
Joined: Oct 2007
Posts: 7,455
Likes: 977
From: RI, Now Franklin/Nashville TN
Fuel Gauge Issue-78
Last time I took out my 78, the fuel gauge would go from reading accurately to the needle swinging all the way to the right way past the full mark. After a minute or two, the guage reads normal again. It happens intermittently. I am sure that others have had the issue and can save me some time diagnosing the issue. All the other gauges in the center pod work fine. Is the gauge bad and I just need a new one? Is it the wiring schematic in the gauge cluster, a resistor, or in the tank from the sending unit? Any help would be appreciated! Thanx.
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
Swinging to full usually means the green sender wire is not making contact (if you pull the sender wire off the tank sender the gauge should go to full).
If the ground is bad to the tank sender it will act the same.
If the large connector in the back of the cluster is making intermittent contact it will act this way.
Clean the green sender wire connection at the tank and also the ground connection and see if that helps.
If the ground is bad to the tank sender it will act the same.
If the large connector in the back of the cluster is making intermittent contact it will act this way.
Clean the green sender wire connection at the tank and also the ground connection and see if that helps.
Thread Starter
Le Mans Master
Joined: Oct 2007
Posts: 7,455
Likes: 977
From: RI, Now Franklin/Nashville TN
Thanx to both of you. I will try cleaning the green sender wire and the ground at the tank and if that does not work I will check the gauge connection in the dash cluster. All else fails, I will replace the gauge.
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
remove green from tank -needle should go to full
ground green -needle should go to empty
Ground and unground green-needle should move semi slow-not too fast
Racer
Joined: Jun 2009
Posts: 409
Likes: 3
From: St. James, NC
I broke the ground on my left taillight housing....was susprised it still worked. Drove the car and noticed the fuel gauge needle swung way over past full (aroud 3 o'clock position). After a few minutes it was reading normal. Happen again...noticed everytime I stepped on the brake the fuel gauge needle would swing over past full to 3 o'clock. Foot off brake, fuel gauge would slowly return to a normal reading. The taillight was grounding through the fuel tank sending unit. Fixed to ground in the taillight and no problems with the fuel gauge since. Just something to consider if the other suggested fixes don't cure your problem. My read of the chassis wiring diagram suggests the taillight was grounding through an alternate path with the tank sending unit.
Thread Starter
Le Mans Master
Joined: Oct 2007
Posts: 7,455
Likes: 977
From: RI, Now Franklin/Nashville TN
I broke the ground on my left taillight housing....was susprised it still worked. Drove the car and noticed the fuel gauge needle swung way over past full (aroud 3 o'clock position). After a few minutes it was reading normal. Happen again...noticed everytime I stepped on the brake the fuel gauge needle would swing over past full to 3 o'clock. Foot off brake, fuel gauge would slowly return to a normal reading. The taillight was grounding through the fuel tank sending unit. Fixed to ground in the taillight and no problems with the fuel gauge since. Just something to consider if the other suggested fixes don't cure your problem. My read of the chassis wiring diagram suggests the taillight was grounding through an alternate path with the tank sending unit.
I will double check when the gauge goes past full but I am fairly certain that it does not happen when I step on the brake, but readomly just driving down the road. Thanx for the additional tip.
Thread Starter
Le Mans Master
Joined: Oct 2007
Posts: 7,455
Likes: 977
From: RI, Now Franklin/Nashville TN
I have never had to fool with anything in the tank area since I have owned the car since 1983. Where is the green wire going to the sending unit on the tank? I figured I would ask before I crawled under the rear. Thanx.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
