[Chevy3+3]

Ok first of all you should be injecting fuel when your cranking. That can be controlled by several things as many have mentioned above. One other thing which can be overlooked is do you have dual tanks? Sometimes the switch in the dash can go bad or be stuck between the left & right tank position.

Another thing is if you have spark but it won't start even if you dump fuel down the bores them your timing has almost gotta be off. You need to wait for #1 cylinder to come up on compression stroke. When it starts building pressure then take a straw or screwdriver and insert in the spark plug hole. Slowly crank the motor over by hand until the straw or screwdriver quits pushing out. Once it stops pushing out you need to see if your rotor on you distributer is pointing close to the #1 plug wire. If it isn't then your timing is off.

If for some reason your distributer is 90° off instead of 180 then you will most likely need to re-index the slot in the oil pump shaft so that it lines up with the orientation of where the distributer drive gear needs to be to make the rotor point at #1 plug wires. Once you get it started you will need to set the initial timing with the ECM wire unplugged usually located around or under the brake master cylinder. It will be a single brown wire most likely with a black quick connect plug.