For Mig 21 SPS , basically the same as BIS only fuel quantity is different:
Tank 1 , Refuel
Tank 2 connected to Tank 3, Fuel Pump 10K Ltrs. per h
Tank 3 Feeder Tank, 18K Ltrs. per h , inverted flight pump
Tank 4 normal tank
Tank 5 Has 450l Signal in lower part
Tank 6 normal Tank
Lights :
700-1000L 1. Group
450- 500L 450L Left
250-350 L 3.Group
below that - Feeder Tank