Skip the auto shop - Our mechanics make house calls

Q: My new gas gauge should read from about 10 o'clock for empty and about 2 o'clock for full. My needle goes to about 5 o'clock.

asked by on

I have a 54 Chevy 3100 P/U. The original gas gauge was not working. I suspect the previous owner burned it up when they converted to 12v. I can put a volt meter on the lead wire and it reads 12v to ground. I purchased a new 12v gauge. When I installed it, the needle on the gauge swings past full and buries the needs almost 180 degrees opposite the half tank mark. If referencing a clock, the gauge should read between about 10 o'clock for empty and about 2 o'clock for full. My needle goes to about 5 o'clock, way off the scale. Nothing changes when I disconnect the sending unit. The needle does swing back when I disconnect the lead to the gauge. Do I have a bad (new) gauge, do I have a bad (miss-matched sending unit, should be 0-30 ohms unit) or could I possibly have the two wires on the gauge reversed?

My car has 100000 miles.
My car has a manual transmission.

A: You would need to see if the sending unit i...

You would need to see if the sending unit is shorted to ground. If you test it with an ohm meter you should get somewhere between the 5 and 30 ohms. If you are getting 5, then the gauge will be at full; and if you get 30, it should be at empty. If you are reading too low on ohms, then you have a shorted sender. If you'd like some help looking at this, a technician from YourMechanic can come to your car's location to inspect your electrical system in person and let you know how to best proceed.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Save up to 30%

Get a quote

What others are asking

Q: Engine has a misfire

There are a number of things that can cause poor fuel mileage, which may also cause it to misfire. A faulty camshaft position sensor is one of them. The camshaft position sensor is a magnetic sensor that monitors camshaft speed...

Q: I just bought a used 99 Honda Accord V-6 2-door and I noticed steam or smoke coming from under the hood, at a drive thru

Hello, thanks for writing in about your 1999 Honda Accord. From what you've described, I think your issue is fairly simple. You probably just need a new thermostat. However, to avoid any unnecessary repairs, I would recommend having one of...

Q: Jeep running rough

An older vehicle like this requires a lot more hands-on tuning and adjustment. Things such as timing, dwell, spark plug, point gap, and carburetor adjustments all should be finely tuned. Getting a vehicle running requires knowledge of those adjustments and...

Related articles

P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.