I finally bit the bullet and dismounted the fuel pump today.
I did that without removing the passenger seat as mentioned in the TIS
I Had to build a tool to unscrew the big nut, so it went rather easily.
After the pump removal a quick inspection revealed that the ceramic
substrate where the resistors are inked was broken into several parts. Only
two were remaining in place. I know I didn't force in any manner to pull the
pump. It has cracked _before_.
In the middle of the substrate, the tracks are almost burnt. The failure
might due to a thermal shock in this point.
Moreover, one side is more worn than the other. I didn't think to check if
it was on the full or the empty side.
This allows to assume that the substrate has been mounted askew.
I put the guts back to the thank, waiting for ordering a new pump.
I took some pictures of the job, incl. the tool. If any interest, I'll put
them on a server. Let me know.