If you look at a in tank pump and assembly when its apart, the positive and negative wires actually sit in the gasoline. The pump uses the gas for self lubrication. Alot of times the windings in the pump just get gummed up and also the springs and brushes get stuck. NOW DON'T THINK ABOUT TAKING IT APART AND FIXING IT LOL. Its a sealed unit, I was just curious one day and took apart a failed unit. Cleaned it up inside and it ran, then I threw it out in the junk barrel. Your fuel pump runs constantly when the vehicle is running! It doesn't shut off and kick back on. It just does that when you go to start it, for example when you turn the key to start but don't crank it, it will cycle, run and shut off, but once its running it will run all the time.
Understand, there'* a filter on the bottem of the in tank pump as well. Called a pump strainer filter. You have to remove the in tank pump and put a hose in there and attach a filter somehow. Now you need to realize that the pump in there maybe plugged up. Picture it as a heart, 1 inlet and 1 outlet style. If its plugged up a little, a inline won't get the proper amount of gas to the motor. 2nd A in tank pump is made to push fuel out to the motor, not to be used as a hose/straw. It just won't flow right, I don't care what walbero says. Its just simple math and thinking. If someone is partially choking you, you may breathe a little but its not the same as breathing normally. Thats about the easiest I can put it.