Also, keep a small piece of insulated wire in your trunk (14AWG or so) with the ends bared. In a pinch, insert this to short terminals 7 and 8 on the relay holder with the relay removed (works on my 1990 560SEL) to get the fuel pump running - gets you home - but remember to pull the wire as the pump will continue to run when the ignition is shut off.

You lose the rev limiter this way, so be careful.