Car constantly backfires

Good morning,

The fuel pressure regulator is part of the fuel pump. You would need to replace the pump assembly.

https://www.2carpros.com/articles/engine-backfires-while-running

I posted the procedure below and some pictures for you to view.

I would start there as they may take care of the entire issue.

Roy

Removal and Installation

REMOVAL

WARNING:
Read General Precautions before working on the fuel system. Refer to "General Precautions".

1. Check fuel level on level place. If gauge indicates more than the level shown in figure (full or almost full), drain fuel from fuel tank until gauge indicates level shown in figure or below.
In case fuel pump does not operate, take following procedure.
a. Insert fuel tube of less than 25 mm (0.98 in) in diameter into fuel filler tube through fuel filler opening to draw fuel from fuel filler tube.
b. Disconnect fuel filler hose from fuel filler tube.

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c. Insert fuel tube into fuel tank through fuel filler hose to draw fuel from fuel tank.
As a guide, fuel level becomes the position shown in figure or below when approximately 10 liter (2-5/8 US gal, 2-1/4 Imp gal) of fuel are drained from fuel tank.
2. Perform The Fuel Pressure Release Procedure from the fuel lines. Refer to "FUEL PRESSURE RELEASE".
3. Open fuel filler lid.
4. Open the filler cap and release the pressure inside the fuel tank.
5. Remove woofer rear speaker or tray of rear floor box. Refer to "LUGGAGE FLOOR TRIM".

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6. Remove inspection hole cover for main and sub fuel level sensor unit.

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7. Disconnect the harness connector and fuel feed tube.

Hello thanks for using 2CarPros.

it seems you have bad fuel pressure regulator,at idle fuel pressure must be 51 psi check fig 1 check fig 2 how to install the pressure gauge.check fig 3 for procedure for checking pressure regulator fig 4 for location.
to make sure from the function of the oxygen sensors check the fault codes and read live data for the function of the oxygen sensors and fuel trim.send us the results.

these is our guide for more diagnosis for black smoke:

https://www.2carpros.com/articles/engine-black-smoke
https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

let us know what happens with you.