AE86 4age engine not starts crank ok backfires to air intake

[totta Crolla]

Fuel can leak past injectors into the the cylinders and the fuel rail is under pressure even with the engine turned off.
I guess the easy test would be to very carefully loosen the fuel rail feed pipe (make very sure that no fuel is spilt that could ignite) to reduce the pressure, tighten it and then remove all of the spark plugs, wind the engine over for a few seconds on the starter motor to remove any fuel residue, dry the plugs and replace them. Turn on the ignition to check for fuel leakage at the fuel rail.
If ok try to start the engine.