I just replaced the in-tank pump and the fuel filter on my 1990 240. Here's some things to be aware of:

1) The car would not run with less than a quarter-tank of fuel -- A clear indicator of an in-tank pump failure.

2) After opening the system to replace components, it took many, many, many, many, many tries to re-start the engine. Following each attempt to restart, its important to turn the ignition completely off before trying again. Both fuel pumps energize briefly when the ignition is turned to the "on" position. This primes the fuel system.

3) Conclusion: if you've opened the system to replace parts and they are installed correctly (big "if" -- is the arrow on the new fuel filter facing the right direction? You jumped the main fuel pump, but is its electrical connection attached, correctly?), but do not have a functioning in-tank pump nor enough fuel to compensate, it's not unreasonable to find that its difficult to restore enough fuel pressure to start the car. Pouring fuel in the front of the engine does not cause fuel to flow through the lines, since the pumps work essentially independent of the engine (they're electronically controlled). That technique worked better in the old days of mechanically-controlled fuel pumps driven off the engine camshaft (like on my '53 Chevy).

I'd install a new in-tank pump with a new strainer sock, ensure there is adequate gas in the tank, make sure the fuel filter is properly installed and double check with your shade-tree mechanic to ensure that nothing else was touched, such as wiring.

For a beginner this at least a full Saturday afternoon job, possibly more with the trial and error process. Unfortunately, a spouse who believes the car is competition with her may make this discussion moot.

Hope you can get both problems fixed, and best of luck!