I've been trying to fix an engine immediately dying after a start for 2 weeks. The issue happened after cleaning the throttle body. For the sake of completeness, below are my other relevant threads within the 2-week time frame:

https://carkiller.com/scottykilmer/qa/engine-keeps-dying-after-cleaning-throttle-body-and-maf

https://carkiller.com/scottykilmer/qa/can-a-stuck-open-egr-valve-cause-an-engine-no-start/

https://carkiller.com/scottykilmer/qa/how-to-check-that-the-timing-is-correct/

Previously I tested that a spark happens on a main high-tension cord (from the ignition coil to the distributor).

Today I tested a spark plug #1 using an ignition spark tester and found interesting new details:

The spark tester blinks (spark happens) with all fuses in place. However, it does not blink (spark does not happen) with the fuel pump fuse EFI removed!

I checked the ignition system diagram and found out that the EFI fuse is not involved. The following fuses and relays are involved in the ignition:

Fuses:
30A IG2
15A AM2
50A MAIN

IG2 Relay
Starter Relay

EFI 20A fuse has the following description: Electronically controlled automatic transmission system, multiport fuel injection system / sequential multiport fuel injection system

Thus, does that mean that I have a short circuit somewhere so that unintended voltage goes to either ignition or fuel delivery from the fuel delivery/ignition respectively? What I could do to find the short (that can be intermittent)?

Or maybe I am wrong and this is intended to prevent spark if the fuel pump fuse is removed?

Car: Lexus GS300 1995 1st gen; Engine 2JZ-GE; 250k miles; automatic transmission.