EKKI:
If you have not already, I suggest pulling both relays and jumping in turn both primary and secondary relay receptacles for relay blades #3 and #5 while listening to hear if each pump is running. It is not necessary to turn the ignition on. I do this check routinely on a 6 month basis. It also gives the secondary pump a little exercise to prevent being pickled in gasoline.

 

Thanks for your input, guys.

I have tinkered a bit in the meantime. This is the current 'status quo':

Both FP-relays installed - car won't start (cranks, tries to ignite but dies off almost instantly)

FP1 relay installed - same as above

FP2 relay installed - car starts immediately BUT restricted performance upon next start and code P1230 (probably refers to missig FP1 relay)

I switched relays, made no difference.

 

Found this thread in the meantime -

https://www.jaguarforums.com/forum/x...-around-31160/

Problem seems likely to be the primary fuel pump.

 

Thanks again for you help, guys - highly appreciated.
Since I have a Coupe AND a subwoofer, replacement of the primary fuel pump might be somewhat easier. We will see.

Btw, any idea where the secondary fuel pump is located? Thanks!

 

The secondary fuel pump is also located in the fuel tank along with the primary fuel pump.