as soon as you start the vehicle it should register
Because you probably damaged the sending unit or the wiring attached to it, or else it was loose or broken to start with.
fuel gauge not working
are you sure you reconnected the wire to the gauge when you did the fuel pump? also the gauge requires a good ground to the tank. its possible you don't have a good connection. just some thoughts.
A common problem with Honda cars is that the fuel gauge is stuck on full. This problem is solved by replacing the gauge cluster.
If the gas gauge in your 1998 Plymouth Breeze stopped working after replacing the fuel pump, it could be due to a few reasons. The fuel pump replacement may have inadvertently disconnected or damaged the wiring or connector for the fuel sending unit, which is responsible for signaling the fuel gauge. Additionally, if the new fuel pump did not come with a compatible sending unit or if there’s an issue with the gauge itself, it could also lead to the gauge malfunctioning. Checking the connections and ensuring the components are compatible would be a good place to start for troubleshooting.
either the fuel gauge needs replacing or the fuel gauge sending unit in the fuel tank is stuck
Start with the fuses. Check the fuel sending unit at the fuel tank, this is the most common part to cause a non working fuel gauge.
Most likely the sending unit in the tank. Start there.
In most cases the fuel gauge sending unit inside the fuel tank is at fault.
The cause of the faulty fuel gauge is probably the fuel gauge sending unit located inside the fuel tank. Replacing the sending unit would require dropping the fuel tank.
possible bad ground
No, not if the pump is working.