Now Tommy Howell or a bunch of other guys have more detailed knowledge, but this will give you some idea what is going on when you watch a Mech Fuel Injected car make a pass.
The Fuel tank-usually 7-10 gallons. The Nitro tanks are bigger yet. They can be made out of alum or composite. The composite ones are purchased at a chassis shop usually when they are building your car so it fits properly. If it is alum, it needs to be anodized so the alum/Nitro won't eat into it.
Main feed from tank to pump inlet-Alum pipe in the 1.25-1.5 diameter. Then using rubber hoses to connect to the pump and tank.
Fuel Pump-this is the heart of the system and must be maintained for performance and consistency. Alky pumps are in the 18-20 gallons per minute range. A-fuel cars are in the 40-50 gallon per minute range and Nitro pumps are from there on up into the 96-gallon range. They may even be more on the current big show cars.
Fuel Shut-off-this is mounted on top of the fuel pump. These are called a 3-way as the fuel has a 3rd outlet so when you pull the fuel shutoff, the fuel will be diverted back to the tank so it won't damage the pump from a dead head situation.
Barrel Valve-if the pump is the heart of the system, then this is the brains. The barrel controls where the fuel is directed into the system. There is an outlet for an idle return, a pump saver, hat, and port feeds. At idle your barrel is returning unused fuel to the tank, it is also sending fuel to your hat injector nozzles so the engine will run.
Pump Saver-this is nothing more than a by-pass canister with a hi-pressure opening point so that at the end of the run when you snap the throttle blades shut, your engine rpms are over 8000, which means you pump speed and flow are way up, now you just shut down all but the idle amount of fuel going to the engine. Since this would cause a major pressure spike, the pump saver opens, and bleeds off fuel and pressure, thereby saving your pump from damage.
Hat Nozzles-these are the nozzles right under the injector hat, and usually also plumbed into the supercharger. Some racers run these nozzles only. They stagger to nozzle sizes to get the fuel distribution as close as possible for all the cylinders.
Port Nozzles-these are the nozzles plumbed into the intake manifold right above the valve covers. These are the nozzles used to add additional fuel for the higher horsepowered cars. This is also the most common place to stagger the nozzles to balance the cylinders for fuel flow and even burning.
Port Check-this is a by-pass canister that is set at a certain pressure to keep the fuel from entering the port nozzles until you want it to. Usually the port nozzles are opened right at the hit or just after depending on the tuner.
Down Nozzles-these are the nozzles that are actually in the cyl head. There is a fuel rail inside by the rocker arms. These nozzles feed the engine only in the run, and inject the fuel right into the cylinders for the most direct spray possible.
Hi-speed-this is a by-pass that holds a pill {jet} to control the flow after it opens based on system pressure. This is used to taylor the fuel curve to the engine needs.
Pump Loop-this is a line added to the outlet side of a fuel pump that directs excessive fuel back to the tank. This can also be called a pump sizer, as that is what it actually does.
I hope this helps give some idea of what a fuel system contains. This is not a complete list and I have only given the most basic of descriptions on the functions.
Rapid
Spell Checked for the Dr. in the house!
I ove it also 
here is something i didn't know. it makes good sense to me as i assume pro stock still uses electric fuel pumps. part of the procedure is turning off the pumps after the burnout to keep from flooding the engine at idle and backing up then turning them back on before staging.... Wally , how long has this procedure been in place and how much pressure(s) are used today?
