fuel pump cycles on and off when car is off along wiht a p1457 code
 

Ok I'm stumped on this one. I have a 2000 DX civic that has a p1457 code and I still working on finding it's cause. I'm told that it's normally on top of the tank and the lines / valve on top of the tank. Droping the tank is a fun job. I'm still keeping an open mind that the PCM could be bad since Accords in the same years would short the ECM if the valve on the canister get wet. The purge control valve never opens and I'm told that if the valve on the tank is bad the ECM goes into by pass and never opens the purge control valve. Does any one know if this is correct?

As far as the pump it could be related to the p1457. When the car is off and sitting in the drive way the pump cycles on and off by itself. Everyonce in a while I will hear a motor run at the back of the car. Besides the fuel pump that all that I know of back there. So why would the pump do this unless the ECM is shot and it does not know what it's doing.
Anyone have any ideas on this one?

By the way I did replace the gas cap even though I knew that was not the problem.