In the fuse box of my 1996 ford e150 van there are 3 black square relays in a row front to back which is fuel pump relay module?

There's no way to definitively tell you which of the three black square relays in your 1996 Ford E150's fuse box is the fuel pump relay without a wiring diagram specific to your van's year and options. The position isn't standardized across all E-series vans.

To identify the fuel pump relay, you need to:

1. Consult your owner's manual: This is the best place to start. It might have a fuse and relay diagram.

2. Find a wiring diagram: You can search online for a wiring diagram for your specific 1996 Ford E150 van. Be sure to specify the engine size (e.g., 4.9L, 5.0L, 5.8L, 7.5L) as this will affect the wiring. You can usually find these diagrams on sites specializing in automotive repair information (some are subscription-based).

3. Use a multimeter (safest method): With the van's ignition OFF, use a multimeter to test continuity across the terminals of each relay. The fuel pump relay will usually show a path when the ignition is switched to the ON position (but the engine isn't started). You'll need to find the correct wires connected to the fuel pump relay in the wiring diagram. Caution: Be very careful when working with automotive electrical systems.

Important Safety Note: Incorrectly identifying and tampering with relays can damage your vehicle's electrical system or even cause a fire. If you are unsure, it's best to have a qualified mechanic perform this task.