No power to the fuel pumps.

2 options: 1) do it yourself with a wiring diagram and a test light 2) find a good, honest Merc expert- you will need one, eventually-

You can try and replace the fuel pump relays and check your fuses........

This can be caused by a bad ground wire,if relay,s and fuse,s are good.

Change the fuel pump relay. I believe it's on the firewall. If you already changed the fuel pumps, the relay should be changed with it.

The Benz I have is 1985

U won't be able to test Fuel-pump Voltage unless someone else is cranking the Engine while U measuring 12 V. However, verify fuel pump Relay is good !!