fuel system on 1990 Oldsmobile 98

what would cause fuel pump to only run couple seconds and turn off when ignition turned on. I changed in-frame filter and before connecting front of filter I turn on car pump only runs a couple of seconds then stop.

Asked by for the 1990 Oldsmobile 98
the fuel pump is only supposed to prime for about 1-2 seconds when you turn on the key, if the computer does not see an RPM signal from the engine, then the computer turns off the pump. This is a safety feature in case of an accident, and the car is damaged and the fuel lines are leaking. The pump will be turned off by the computer, if the engine is not running, so the fuel does not spray all over and cause a huge fire.