fuel pump woes

[mschluns]

i own a 1975 mercedes 450 slc, my fuel pump quit working and i have been trying to troubleshoot this problem, i unhooked the wires from the fuel pump and have no power with the ign. key on, i have continuity threw the ground wire. i know that the fuel pump relay should kick in after the ign switch is turned on, i am not quite sure which relay it is, thers are 2 banks of 4 ea, along with 2 more on seperate hangers, these relays are all identical, i pulled them out and looked, there are 2 more larger looking relays on either side of these 10. i believe the fuel pump relay is the upper right relay, of the 2 banks of 4 each, any way if these are all identical i have switched them around and still no power at the pump, i could have a broken wire from here to the pump but i think that is unlikely, any help would be great trying to track this down. does anybody have a good picture of the fuel pump relay and its exact location and maybe some troubleshooting tips. i am hoping its not my control unit but its starting to look that way. thxs mschluns