Vehicle is a '91 300-SEL. Car is fine, but am curious about those MBs featuring independent fuel pump relays and those that are built into the MAS.

I've read about jumpering pins in vehicles
that have independent fuel pump relays. If your MB has it's fuel pump relay built into the MAS, is there a DIYER test available or do things get too complicated at this point?
Thanks for your time.

Mike Murrell