"I jumped the left side of fuse 4 and 6, and heard the relay hum, and clicking from the main fuel pump, but it did not appear to be buzzing and pumping."

Those fuses have nothing to do with the pumps on a '78. I don't know what you heard but it wasn't the pumps.

For your '78 K-jet, fuse #7 powers everything but the Tank pump, which has a separate (unnumbered) 5A fuse in an inline holder back near the pump, but before the wires go down thru the square access plate (I think).

You probably aren't hot to spend any more than necessary, but if you plan to work on K-jet problems, the best starting point is a fuel pressure test. And with K-jet FI, that requires a special gauge setup that can measure not only the Main pump pressure, but "Control" pressure, which is critical to starting and normal running. Without knowing those pressures, it's apt to be just frustrated guesswork and parts swapping.

The best K-jet gauge price and availability that I know of is at JC WHITNEY.
[For comparison, mine cost $97.00 "back in the day".]

Also, your learning curve will benefit greatly from owning and reading the K-jet section in "Bosch Fuel Injection & Engine Management" published by Bentley (stock Number GFIB). The list is $29.95 but I see Amazon has it for under $20.

EDIT: There is no fuse jumpering that will run the pumps on your '78. And you don't have The Frequency Valve that Jesse mentions (unless it's a California car) with the "Lambdasond" Oxygen sensor (in which case jumpering fuses 5 and 7 will run both pumps).

--
Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.