The jumper should do it, IF the spark is there.

1 - Could you hear the pump run? Gotta know that up front.

2 - Did any water get under the hood? Seems like trouble started after the wash.

3 - Did you look at the coil primary wires as I mentioned?

4 - Have you actually pulled a plug to verify a good sparks? I'm afraid I haven't seen a Bosch system failure, but we can see what Bentley says if there is no spark.

I'd pull all the plugs, after trying to start, and:
a) check for signs of fuel (or NO FUEL) on the plugs
b) position 1 or 2 plugs so the body is grounded, and watch for spark while someone else cranks.

It's early for long shots, but maybe the timing belt has issues.
5 - Look thru the oil fill hole to see if the camshaft turns while someone cranks it over.

P.S. It's hard to know what to suggest, without knowing something about your end.
6 - What do you have for tools and experience?

P.P S. Chris Mullet has a point. The coil gets primary +V by different routes when cranking vs running.
7 - Is it when you let go of the key that it quits?
--
Bruce Young
'93 940-NA (current) — 240s (one V8) — 140s — 122s — since '63.