if gauge worked prior to pump change then you will need to remove tank & check wiring & condition of sending unit, they are easy to mess up putting pump down in tank. if it didnt work prior to pump change then replace sending unit.
Faulty fuel pump.Dirty/plugged fuel filter. Blown fuse. Faulty fuel pump relay. Faulty wire harness/connections. Empty fuel tank (faulty gauge).
Clogged fuel filter, defective fuel pump, blown fuel pump fuse, defective fuel pump relay, or it is out of gas and you have a faulty fuel gauge.
The gas gauge shows "E". The fuel filter may be plugged. The fuel pump may be faulty. The fuel pressure regulator may be faulty.
Faulty fuel pump. Faulty fuel pump relay. Faulty fuel pressure regulator. Clogged fuel filter, pickup, or line. No fuel in the fuel tank.
There is nothing to reset. After you replaced the fuel pump/sending unit assembly the gauge should have worked. Could be a faulty new sending unit on the new assembly. I had that happen with an aftermarket pump assembly. Bring it back and exchange it for another one.
A faulty fuel pump or faulty wiring to the fuel pump. Be sure to replace the fuel filter also.
Blown fuse. Bad fuel pump relay. Faulty new fuel pump. Faulty wiring. Loose/rusty ground connection. Faulty fuel pressure regulator.
Either the gauge is faulty, there is a broken or shorted wire between the gauge and the sending unit or the sending unit is faulty. Hopefully, it's not the sending unit; That's integrated with the fuel pump module inside the fuel tank and to replace it means replacing the entire fuel pump module. Not a fun chore, and requires the removal of either the fuel tank or the truck box (take your pick, one method is about as much work as the other).
could have faulty or dirty contacts, pump motor could be bad or the pressure gauge is faulty
You may have a leaky fuel injector or a faulty check valve in the fuel pump. I vote for the faulty fuel pump.
There are many different reasons for that... It can be faulty fuel pump. It can be low pressure in the fuel line. It can be faulty fuel pump relay and etc.
the fuel pump tank wiring is faulty at the pump