By the way, were you able to test if the fuel pump turns on when switching IGN on?
That green yellow thing definitely belongs to the fuel pump. I think it is pre-filter, if I remember correctly.
The inside of the fuel tank looks good, I wouldn't bother cleaning that much more. That should be OK.
Next up, I would put the fuel pump part back together, wire up the two fuel hoses (direction matters here), and plug the electrical connection.
Put a battery in it, and check if the fuel pump runs for about 10 seconds when turning IGN on.
You can also check if fuel is delivered to the injector.
Be careful when removing the injector. Use perfectly fitting equipment (I think the injector housing is secured with a PH3 screw), otherwise you might ruin the screw head.
Clean the injector in ultrasonic cleaner, and install again.
Good luck!