[ossiblue]

Your 75S does not have a fuel pump relay, that's why it comes on with the ignition switch although it should not start until the switch is "on", not "accessory" as you have pointed out. IIRC, the pump is powered from fuse #7 in the upper fuse block in the front of the car. If you look closely, you should see the red/green striped wired going to the fuse. Check to see the fuse is making contact across the terminals. If so, check to see that you get power from both sides of the fuse. The power to fuse 7 comes from terminal 15 of the ignition switch.

Edit: Ed is correct, see his post below, that the power to the pump is not fused--it comes from the line side of the block and is powered directly by the red/black wire from the ignition switch. However, since your problem happened after going over a speed bump, it's highly suspect that a connection was shaken loose somewhere. It could be the battery cable or the ground at the battery, check that they are secure. Make sure the plug into the back of the ignition switch is seated. Make sure the plug from the ignition harness through the bulkhead into the trunk is seated (look under the dash). Make sure the connection of the red/green striped wire to the fuse block is secure. The wild card here is you have some non-factory wiring that may change these connections. If you can post a picture of the fuse block in the front, where the fuel pump wire is located, that could help greatly.