1996 arctic cat zr 580 efi backfires out of the exhaust and intake

I got an 1996 arctic cat zr 580 efi. I did a top end rebuild on it and put everything back together and tryed to start it and it backfired so i replaced the stator. Then i tryed to start it and it still backfires bypassed the tss switch. But if i swap the injector timing sensor with the igntion timing sensor i will start but it will run like crap also i check the fuel injectors and one is no workng tested it and it is not getting ground :dunno: . i so confused i want to getting running by winter

1996 arctic cat zr 580 efi backfires out of the exhaust and intake