2002 Chevy Silverado 3500 Fuel gauge reads 1/2 when actually empty and with the ignition switch off the fuel gauge jumps to half the vehicle has dual tanks and the fuel pump module in the front tank was changed a week ago.

To troubleshoot the issue, i suggest you few help links with accurate solution step by step:---
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Fuel pump not running?
http://schematicsdiagram.blogspot.in/2012/02/fuel-pump-not-running.html
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Fuel pump not working on 1991 Ford Ranger?

http://technoanswers.blogspot.in/2012/01/fuel-pump-not-working-on-1991-ford.html

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Fuel pump has no power on 2002 ford 350 7.3 diesel?

http://technoanswers.blogspot.in/2012/01/fuel-pump-has-no-power-on-2002-ford-350.html

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Emergency fuel shut switch on Ford car?

http://schematicsdiagram.blogspot.com/2011/12/emergency-fuel-shut-switch-on-ford-car.html

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How to jump fuel pump On Chevrolet Silverado 1500?

http://schematicsdiagram.blogspot.com/2011/12/how-to-jump-fuel-pump-on-chevrolet.html

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How to Increase gas mileage on 2011 2500HD Duramax 6.6?

http://schematicsdiagram.blogspot.com/2011/12/how-to-increase-gas-mileage-on-2011.html
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How to test Fuel Pressure and replace Fuel Pump?

http://repairhelpcenter.blogspot.com/2011/11/how-to-test-fuel-pressure-and-replace.html
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Fuel Running Lean

http://technoanswers.blogspot.com/2012/10/fuel-running-lean.html
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How to relieve fuel pressure?

http://technoanswers.blogspot.com/2012/01/how-to-relieve-fuel-pressure.html

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Refueling problem?

http://repairhelpcenter.blogspot.com/2012/01/refueling-problem.html

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Toyota Tercel consuming more fuel?

http://repairhelpcenter.blogspot.com/2012/01/toyota-tercel-consuming-more-fuel.html

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How to maximize fuel economy on your vehicle?

http://schematicsdiagram.blogspot.com/2011/11/how-to-maximize-fuel-economy-on-your.html

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Fuel gauge jumps from empty to full?

http://schematicsdiagram.blogspot.com/2011/12/fuel-gauge-jumps-from-empty-to-full.html

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Gas gauge stuck on empty on 2002 Mercedes Benz 240c?

http://repairhelpcenter.blogspot.in/2012/02/gas-gauge-stuck-on-empty-on-2002.html

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No power to the control side of the fuel pump relay?

http://schematicsdiagram.blogspot.com/2011/12/no-power-to-control-side-of-fuel-pump.html

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These will help.

Thanks.

Check spark plugs, leads, distributor cap & rotor arm, fuel pump, fuel filter, coil pack(s), relays, replace any items that are suspect IE Fuel filter which has probably not been changed since new even though they should be changed on all vehicles every 18 months, all of this can be done at home & will save you a lot of bucks in mechanic/garage fees,

David Johnson is wrong about that. The Chevy HD dual tank has two sending units, one in each tank , one fuel pump, a fuel pump relay switch and a equalizing pump. If the truck stalls out at 1/2 tank, it is the equalizing pump. That pump, pumps fuel from the rear tank to the front. If the pump is out, the front tank empties, the truck shuts down, the guage reads half tank because the back tank is still full, but the equalizing pump won't pump the rear fuel tank load to the front. Hence the problem you listed above, not a sending unit.

Common problem on the 03-06 Silverado instrument clusters for the fuel gauge to go out. It's usually caused by one of two main problems, either the stepper motor on the cluster's circuit board is going out or the sending unit on the fuel pump is going out. Check out this blog post about the problem - Silverado fuel gauge problems

sounds like a fuel pump/sending unit.. a pump normally just quits with no warning..

COULD BE THE FUEL SENDER OR YOU HAVE A POOR GROUND POINT IN THE CABIN.
WEIRD AND MULIPLE MALFUNCTIONS ARE USALLY A POOR GROUND.

Fairly common problem with GM vehicles. The sending unit in your tank has a small circuit board that an arm is attached to which moves up and down according to your fuel level. This circuit board and arm are not making good contact. Unfortunately the only good solution is to replace this part.

Hi I have a 4x4 2003 chevy 3500 silverado dually with dual tanks
rear tank stoped pumping into front tank and was full . I siphoned the fuel out of rear tank and fuel gauge reads 9/16 full . is there a way to reset the fuel sending units so they can calculate the fuel readings. I always filled the two tanks with the same amount of fuel
until now ? I'm thinking there is a inkine fuel pump

Youre gauge is controlled by a plunger in the fuel tank which is attached to the sensor and the fuel gauge. it sounds like when the plunger goes down half way its either getting stuck down lower then it should. Needs replacing. Any mechanic can do this install for you.

Could be a
1. Fuse - not likely, I'd expect other instrument panel problems.
2. Broken wire from fuel gauge
3. Bad fuel sender in fuel tank. Normally requires dropping the tank.

Vehicle is not that old, would think it is still under warranty?