Unless someone has installed an aftermarket electric fuel pump in your truck, turning the key to the ON position is not going to do anything for you fuel-wise. The lift pump (the pump that sucks the fuel from the tanks and pushes it to the injection pump) is mechanical, meaning it only works when the engine is running.

That being said, plenty of folks have replaced their mechanical lift pump with an electric one. It's a great upgrade and could help with your starting issues from an air intrusion standpoint, though that's really more of a band-aid than anything else as far as that goes.

When your GP system is working properly, you should get one click from the solenoid, though to be honest, it's not always audible (at least in my truck). If you get multiple clicks combined with a very short WAIT TO START light, that usually indicates bad glow plugs. If you don't get any clicks, my money is on a bad GP solenoid, wiring, or some previous owner got in there and monkeyed around with something they shouldn't have.

Mike