[ngoma]

Can be frustrating. Very small leaks can still produce enough odor for the human nose to perceive.

Some IP leaks can be difficult to uncover. Can you wipe a clean paper towel along the extreme underside protruding ridges at the bottom of the IP? If that picks up fuel moisture there is a small IP leak somewhere. Commonly at the mainshaft seal or at the distribution head large diameter o-ring seal. The throttle shaft seal is another common leak area but you would be able to see this easier.

One time when I had persistent fuel odor yet no evidence of leaks it was the deteriorating injector fuel spill lines that were damp with fuel on their outer wrapping. No dripping leaks yet squeezing them released fuel like a sponge.

Have you looked at the fuel tank, cap, fuel rails?

Any way apparently you are way more advanced than I, who have never used UV equipment to discover leaks.