i have a Buick 2003 century that will not start. Spray gas in the Air intake it starts and runs find. turn engine and it wont even try to start. I have 50 psi in injector rails.

Do a fuel bleed down test by having your fuel pressure gauge hooked up, build up fuel pressure and turn the key off. The fuel pressure should not really drop but maybe 5 lbs.

Also may have to check to see if you have injector pulse at the fuel injectors.

Did fuel pressure test it holds at 50 psi. That's what I'm thinking that the injectors are not pulsing when I'm cranking the engine. but why when i put fuel in the air intake tube it starts and runs fine at all speeds? The injectors have to be working fine then.

Good morning Albea, So when you get the car started, you say you can drive it until you turn it off? Or does the engine run until the fuel is all burnt out after putting some into the intake? If this is the case the ignition system still works and is just igniting the fuel that was put into the intake until it is all burnt out. Injector pulse needs to be checked when someone is turning the key to the start position. You know, another thing may be that the security system may be activated and needs to be reset. This shuts down injector pulse during trying to start the car. May just need to reset the security system.