Car will turn over but wont start

Is that a 20-amp fuse you are replacing? As I used to ask my students, "how many fuses you going replace and pop before you realize there must be a better way to troubleshoot this"? That better way is,

A simple trick to finding a short is to replace the blown fuse with a pair of spade terminals, then use small jumper wires to connect them to a 12 volt light bulb. A brake light bulb works well. When the circuit is live and the short is present, the bulb will be full brightness and hot so be sure it's not laying on the carpet or against a plastic door panel. Now you can unplug electrical connectors and move things around to see what makes the short go away. When it does, the bulb will get dim or go out.

You already started the process of elimination, but fuel injectors rarely short. It is much more common for a wire to rub through and ground out. What you should find is the test bulb becomes full brightness for one second when you turn on the ignition switch, then it will go off. It will be full brightness again during engine rotation, (cranking or running). It is not practical to troubleshoot this circuit while cranking the engine. A better way is to bypass the fuel pump relay. It should have four terminals. One of them will have 12 volts all the time when the ignition switch is on, (and the fuse is not blown or the test bulb is in its place). You need to jump that one to the one diagonally opposite it. Now the circuit will be live and the test bulb will be bright when you turn on the ignition switch.

Follow the injector harness to a large plug between the engine and the body. Unplug that. If the bulb goes out, the short is on that wire harness. I suspect the bulb will still be bright. If it is, crawl underneath and unplug the fuel pump assembly at the gas tank. It is extremely rare for a fuel pump to short, but suspect that if the bulb goes out. If it stays bright, you will need to follow that harness to the short. On a lot of GM cars, the wiring harness runs under the carpet under the driver's feet. That is just asking for wires to rub through and ground out. You will know when you disturb the short by observing the test bulb flickering or when it goes out.

Check to see if the wires up to the fuel rail rubbed bare against the fuel rail. I have seen that before.

There is a few different issues the fuel pump should have a separate fuse from the injectors.I would do one at a time start with the injector fuse.

I was just going to say the same thing. Pick one circuit and start with that. Once that is solved, we will see if we need to start over with the next problem. When my students were diagnosing my prepared "bugged" cars, they learned very quickly that "run a new wire to replace the one with the short" was not an acceptable answer. We need to find the exact location and cause of the problem, and fix it there for exactly the reason Saturntech9 described. A wiring harness could by laying on the sharp edge of a metal bracket. It could have fallen down onto hot exhaust parts. It could be rubbing on body sheet metal as the engine rocks back and forth. In all of those cases, it's just a matter of time before the same thing happens to the next wire. You can avoid the heartache of having to do the next diagnosis by correcting the cause right away.

I am not sure on the wiring diagram which fuse is blowing, but using the light bulb in place of the fuse still applies. You need to do whatever it takes to power up the circuit, then the bulb will be full brightness as long as the short is present. If the harness is rubbed through and a wire is grounded by the fuel rail, all you need to do is disturb that harness. You will see the bulb flicker when you do anything that causes the short to go away momentarily. By "disturbing" the cause of the short, I do not mean yelling at it! :) I mean moving the affected wire or unplugging something that isolates the short from the fuse box. For example, even though it is very unlikely, if one injector was shorted, the test bulb would go out as soon as you unplugged that injector. Before you got that far, the bulb would also have gone out if you had unplugged the large harness going to the entire engine. At that point you'd know you were on the right trail. You would narrow it down by unplugging each injector until you found the one that made the test bulb go out.

(Actually, this is a bad example because a shorted injector wont cause the test bulb to light up. The injector's circuit is turned off inside the engine computer until the engine is running, so until then, the circuit with the short is not turned on. You would need to have a shorted injector and a shorted driver circuit in the computer at the same time, and neither is very likely).

Similarly, suppose the test bulb went out when you unplugged the large "bulkhead" connector at the firewall. Those usually have up to sixty wires, and many of them feed circuits in the inside fuse box. The procedure now would be to reconnect that bulkhead connector so the short comes back and the test bulb is bright, then remove one fuse at a time from the inside fuse box. When you find the fuse that makes the short go away, you will know which circuit to continue following.