How do fuel injection systems work?

[mtharvey]

I mean the gas tank, fuel injectors, pressure regulator, check valve, filter, canister. I notice that the pressure goes up to 44psi when fuel pump turned on but the pressure than falls to 20 psi if car is not turned on. I was wondering where the pressure escapes to?

[mrlooneytoon]

http://auto.howstuffworks.com/fuel-injection.htm

Go crazy, you might have to do a bit of reading.