FD Leaking on one cylinder

Ok this is a strange on, after a good time running good got a fouled spark plug.
After a long investigaion, ended on balancing the FD... But noticed something very strange, with the plate up, pump running 7 cylinders hace no fuel, but one does... The one that fouled the spark plug, no matter what... Thats cylinder is always getting fuel... What coils be the reason? A failed plunger/barrel???

 

Possible causes might vary depending on whether it's a K-Jet without Lambda, K-Jet with Lambda, or KE3-Jet Fuel distributor (you don't give year/model/version nor is that information in your Profile), but it almost doesn't matter what the cause is as the FD will have to be disassembled/repaired.

 

87 Mondial 3.2
Kjet
0 438 100 139

 

That FD Bosch part number seems to be a US version K-Jet with Lambda FD like shown in this thread:

https://www.ferrarichat.com/forum/threads/308-mondial-qv-mondial-3-2-328-fuel-distributor.657628/

but, as I said, it really doesn't matter what the cause is (could be something like a "leak" between the lower chamber and the upper chamber of that cylinder) as the FD has to be disassembled/repaired/rebuilt.

 

good, the basic question is: have anyone seen a behaviour like this?

i will switch all orings again .... to see if that helps

 

after a deep investigation (and assembling, dissasembling the FD like 5 times) get to the conclusion the issue was sourced in two failed orings, the barrel base oring had a little shave (very fine piece of the oring was spread) and one cylinger oring was too thin.... i think the kit I got had some old / hardened orings, so will use newer ones, probably green ones.