fuel pressure problem

What is the issue your having? I will help you with your vehicle.
Most fuel pressure should remain after shutting off the engine however, not always, it depends on the design the manufacture installed in the vehicle. This is just a generalization and does relate to your Accord.
Please reply

96 honda accord 2.2 L automatic front wheel drive not a VTEC
I did fuel pressure test and these are the result
- fuel pressure at idle and vacuum hose of the fuel pressure regulator connected 33Psi
- fuel pressure at idle and vacuum hose of the fuel pressure regulator disconnected 42 Psi
after that I turned off the engine the pressure was

at 4: 36 pm the pressure was 33 psi
at 4: 41 pm the pressure was 29 psi
at 4: 44 pm the pressure was 28 psi
at 4: 57 pm the pressure was 26 psi
at 5: 13 pm the pressure was 16 psi
at 5: 18 pm the pressure was 14 psi
at 5: 25 pm the pressure was 8 psi
at 5: 37 pm the pressure was 5 psi

the next day the pressure was 0 Psi

the fuel pressure regulator is good it does not let fuel goes back to the tank when the engine is off

and Hmac300 told everything is good. i did the fuel pressure test because the car long cranking when it seats for few hours

Your pressures are within specifications with and without the vacuum hose applied to the pressure regulator.
The pressure is bleeding off some where if its not the fuel rail pressure regulator then there is a leak or the leaks is within the fuel pump itself.
Pressure would bleed off over night would be considered normal.

thank you so much you are helpful

Yesterday i replaced fuel injectors i got some from junk yard i tried to clean them . today the check engine light is on SYSTEM TOO LEAN p0171 .what is the best spay can that i can use to clean injectors?

If the injectors are eletrically sound (the coils are good) then the best way of cleaning injectors is ultrasonic cleaner machine. As for spray a good intake or fuel injection cleaner can help but wont do as good of a job as the ultrasonic injector cleaner.
Either the injectors are no spraying enough fuel (restriction) or you have a vacuum leak.