Died while driving, now crank-no start

[Nightowl]

how did you measure the 12v? Any working motors should run at 12v supply.

Unplugged the pump and used a multimeter while I turned the key to the second position. Once I confirmed that it was getting power/ had ground, I plugged it back in and with a hand on top of the pump, turned the key to second position.

The pump kicked briefly, but did not fully prime/ run. So my thought was that it might be getting 12v initially, but as soon as there's an actual load going through the system, the relay trips.

[sapote]

Unplugged the pump and used a multimeter while I turned the key to the second position. Once I confirmed that it was getting power/ had ground, I plugged it back in and with a hand on top of the pump, turned the key to second position.

The pump kicked briefly, but did not fully prime/ run. So my thought was that it might be getting 12v initially, but as soon as there's an actual load going through the system, the relay trips.

1. you measure the volt between the two wires (going to the pump) and not from one wire to the chassis ground? Have to measure between the two wires.
2. I'm confused. You first said there was 12v during the priming time, then why you think the relay trips or fails? If relay trips then you don't have 12v

To do: with cable plugged to the pump, measure the voltage between the 2 wires and it should have 12v continuously during the 2 or 3sec priming time. Measure the wires with pump disconnected is useless.

[Nightowl]

So, a small update: I had a chance to charge the battery and popped the rear seat up so I could have a hand on the new pump.

It does prime for a few seconds, but after an initially promising prime, removing the key and starting again did not prompt a second prime. Is that normal? I would've expected it to prime again after removing the key and turning to 2nd position again. This is without cranking though, so I guess if there is sufficient pressure in the line, it doesn't prime?

Still waiting for the new(er) EKP module to arrive to try that. I had also hoped to replace the fuel filter this weekend but got rained out.

[sapote]

It does prime for a few seconds, but after an initially promising prime, removing the key and starting again did not prompt a second prime. Is that normal? I would've expected it to prime again after removing the key and turning to 2nd position again. This is without cranking though, so I guess if there is sufficient pressure in the line, it doesn't prime?

Of course it should prime every time the key turned ON for a few seconds.
"did not prompt a second prime" : based on your ears or by the volt meter? You might not hear the 2nd priming bc the pressure had built up and the pump was loaded and not running that fast.