of a bad filter, water in the tank or what ever and you have that pesky bubble or two in the injector pump. That's when you need to bleed the non-self bleeding injector type pump. Just changing the filter shouldn't ever be a problem as long as you don't crank the engine. And why would you when the job is just routine maintenance. Bleeding is always, or most always, due to some sort of problem inserting air into the system. That could be an engine running out of fuel (for what ever reason) or replacing some part of the fuel system like a pump or fuel line. Now you're going to have to go through the process. Fill up the fuel filter bowl, manually pump the mechanical lift pump (or flip the electric switch, much easier!), open the injector bleed valve and bleed the pump, crack one of the injector tubes, open the throttle full and start cranking the engine. IMHO, that's when the electric pump comes into it's own.