2001 F4i. Apologies if this has been covered! Just bought bike as non-runner (been stood, needed fuel pump). Fitted pump, purged fuel system of any residual rubbish, cleaned and sealed tank interior (prior to pump assembly fitment of course). Bike fired up first time and sounded like a Swiss watch - well pleased. FI light then came on, traced to a MAP sensor vacuum hose come loose, but runs only on 1 and 4. 2 and 3 headers absolutely stone cold. Plugs are good with strong spark, and injectors are all firing with a nice even spray pattern.
I can't think it's compression, as it did run like a dream first of all.
Any thoughts?

(Just to confirm, 2 and 3 are not firing, not 3 and 4 as it says in the title)

 

Is there any chance that the connections for the ignition coils got swapped between cylinders #2 and #3? The B/W and Y/W wires/connector should be on cylinder #2.