P0461 I did changed my fuel pump and fuel filter with fuel level sending unit but still can not start.

Yes the fuel tank has to come out to change the fuel pump. But are you sure that is the problem ? Your vehicle has a Fuel Pump Flow Control Module (electronic's ) Or is it just your fuel level sensor you want to replace ? And to your question of if the fuel level sensor is bad will the car shut down if the gage says it is emty but it is not? No ,this will not shut down the vehicle. You probably have no idea of the complexity of the electronic's involved an the thing's that can cause the gauge not to work .
Fuel Gage
The instrument panel cluster (IPC) displays the fuel level as determined by the ECM. The IPC receives a serial data message from the ECM indicating the fuel level percent. The fuel gage defaults to empty if:
• The ECM detects a malfunction in the fuel level sensor circuit.
• The IPC detects a loss of serial data communications with the BCM
• The BCM detects a loss of serial data communications with the ECM
When the fuel level is less than a pre-determined value, the low fuel indicator illuminates in the IPC.
Unless you have a factory or professional type scan tool your better off taking your vehicle to a qualified repair shop.

Fuel Gage Inaccurate or Inoperative
Circuit/System Description
The fuel level sender changes resistance based on the fuel level. The engine control module (ECM) monitors the signal circuit of the fuel level sender to determine fuel level. When the fuel tank is full, the sender resistance is low and the ECM senses a low signal voltage. When the fuel tank is empty, the sender resistance is high and the ECM senses a high signal voltage. The ECM uses the signal circuit of the fuel level sender in order to calculate the remaining fuel level percent in the tank. The ECM sends the fuel level message via the serial data circuit to the body control module (BCM). The BCM sends the fuel level percent to the instrument panel cluster (IPC) via the serial data circuit for display on the fuel gage.

Circuit
Short to Ground
High Resistance
Open
Short to Voltage
Signal Performance
Fuel Level Sensor Signal
P0462
1
P0463, P0464
P0463
P0461
Fuel Level Sensor Low Reference
--
1
P0463, P0464
P0463
P0461
1. Fuel Gage Inaccurate or Inoperative

Do you know what a DTC is ? diagnostic trouble code !

if you have a scanner that reads data go to your data and find out what kind of fuel pressure you have.it should read between 50 and 60 psi. .if you don't have a fuel pressure gauge just push on the Schrader valve and see if you have any fuel pressure after cranking for a while. If you don't have any pressure it's probably the fuel pump.

fuel pick-up in tank is blocked it has a sock over the end as a gross filter to keep out any big junk from getting sucked into the pump and causing damage to it. the sock can get so plugged up that no fuel will flow, causing the pump to run for a short time then with no fuel flow to cool it it trips the safety and shuts off

On rare occasions, the fuel gauge does not read the correct level which may result in a no start condition due to a low fuel level.

Upon further investigation, the technician may find DTC P0455/P0461 Fuel Level Sensor Circuit Performance stored in the ECM/PCM. Test it.

Hope this helps; also keep in mind that your feedback is important and I`ll appreciate your time and consideration if you leave some testimonial comment about this answer.

Thank you for using FixYa, have a nice day.

if you take the time to drop the fuel tank you might as well replace the fuel pump module. this will come with a new fuel pump and level sending unit. DO NOT USE AN AIRTEX brand. they will leave you with more problems! Get an a/c delco or delphi pump. make sure to replace the fuel filter at the same time.

I’m happy to assist further over the phone at https://www.6ya.com/expert/jeremy_d728a59f986299fa

P0461....Fuel Level Sensor Circuit Range/Performance ,

1. The Fuel Level Sending Unit, or Fuel Level Sensor, is located in your gas tank with the Fuel Pump Module. The fuel gauge sending unit (fuel level sensor) is attached to the side of the fuel pump module. The sending unit consists of a float, an arm, and a variable resistor track (card).
2. The Fuel Pressure Regulator is located within fuel pump module. The fuel pressure regulator controls fuel system pressure. The PCM cannot detect a clogged fuel pump inlet filter, clogged in-line fuel filter, or a pinched fuel supply or return line. However, these could result in a rich or lean condition causing the PCM to store an oxygen sensor or fuel system diagnostic trouble code.

Both of these sensors are connected with the Fuel Pump Module. Here is a diagram:


I’m happy to help further over the phone at https://www.6ya.com/expert/jeremy_69f3cc28d95bf514

this code is for fuel tank level sensor, I don't think this is the reason for high emissions, can you give me the emissions results and I'll see if I can give you better advice?

Regards Jim

P0461 reads: Fuel level sensor circuit, range or performance problem.

P0463 reads: Fuel level sensor circuit, high input.

Both codes point to changing the fuel sending unit and, I'm sorry to say, isn't cheap. I recently replaced mine and it ran about $300 for an aftermarket unit purchased from O'Reilley auto parts.