How long should the fuel system hold pressure? I just installed new injectors and noticed that pressure drops in the system, gradually over time. I worked it out to be 6 psi over a period of 20 minutes. Or 0.3psi/minute. Is this normal?

 

Thats not too bad, but not good either. Sounds like the check ball thing that should hold the pressure in the pump is not holding all the pressure. If it gets a lot worse you should replace the pump. A friend of mine had his go bad too, it dropped all pressure within a few seconds ... but he was still able to start the car if he primed it a few times

 

Is this with the car on, or off? I thought pressure drop was only a problem when the car is on, but I'd never considered checking PSI after shutting it down. What's normal?

 

that sounds about normal, it will leak down over time