dvdguy:

First, have you tried actually starting the car with pins 7 and 8 jumpered? It sounds as if your pump and its circuitry are basically alright, but if it won't start with the fuel pump relay installed then the relay is the prime suspect. When the relay is in, the pump should only energize when the key is turned to start. You say there is "no fuel pump action" in this case, but do you have a helper available who could turn the key while you listen for the pump at the back of the car? If you don't hear it humming with the key on 'start' then your relay is the problem. (You'll have to get your ears pretty close to hear the pump over the starter! A large piece of cardboard as a baffle might help.)

Of course, the ultimate test for fuel flow would be a proper fuel pressure test at the fuel distributor. Or, you could disconnect the fuel supply line to the distributor and verify, with a suitable container and plenty of rags handy, that fuel is being delivered. (When you loosen that connection, it is entirely normal for some fuel to spurt out when there is residual pressure in the system. To minimize this, you can depress the airflow meter plate, which will bleed off fuel to the injectors - and give you a very rich mixture when you eventually try to start! Be sure to use a counterhold on the 17mm nut closest to the fuel distributor whenever you work on these fittings.) If there is a blockage somewhere, it is most likely your fuel filter. I don't know whether you replaced that when you did the pump, but it's always a good idea to do so.

All of this assumes that the car is otherwise sound and that there are no issues with compression or ignition. If you do end up replacing the fuel pump relay, make sure you get a genuine M-B part. The aftermarket units, especially KAE, are notoriously unreliable. Potomac German Auto is a good source for used M-B units if you don't want to spend all that money for a new one.