The attached is related to what I call the fuel pump"barrel connector". The image shows the connector on my '94 M104 so its different from yours. Yours should be upright, and wire tied to the bulkhead. This shot was taken while looking down at the positive terminal side of the battery. When connectors aren't tied to the bulkhead, they can easily be pushed apart when the OVP/ECU/ABS area plastic shield is being installed. As the shield is being pushed down, it grabs the connector and the two halves come apart. IIRC, there is no locking feature on the connector so both halves being tied to the bulkhead is all that keeps them together. Its worth checking this before you start digging deeper.
The attached is related to what I call the fuel pump