3-Way Purge Valve Passing Liquid to Liquid Fuel Nozzle


One of our 7FA turbine had high dynamic pressure in can 3 and 4 while running on natural gas and the liquid fuel re-circulation was on. Now the unit is off, and while liq fuel re-circulation is on, the 3 way valve is passing liquid fuel to the liquid fuel nozzle and combustor and it is going to the the false start drain in the 7 lower cans. The problem now we don't know which can has the passing because even if the 3 way valve in can 2 (which doesn't have false start drain) is passing, then the liquid would go to lower cans through the cross fire tube and drain there. Is there a method of knowing which valve is passing without opening the DLN and see through the liquid nozzle while re-circulation is on?

I am relatively new employee but I heard that this is not the first time the 3- way valve is passing in the plant. Anyone experienced this issue and discovered the real cause behind it. This would help me investigate the problem. Thank you
I forgot to mention 2 points.

first, usually we don't run the unit on liquid. it is safe to say that we don't touch the unit from April to September due to the high demand load on hot days. we run it on cold days only, but we use re-circulation all around the year.

second, the false start drains that were found to have liquid in them are cans 4 (the highest amount of oil was coming from this can), 5, 6, 7, 10.
there was no liquid in 8 and 9.
if i understood right, then you can do a false fire attempt. That is done in several ways. One of them is isolate power for ignitors then run the unit on liquid fuel (you should have 30 sec. of fuel flowing). During those seconds you can monitor the fuel pressure on flow divider, fuel check valve that has lower pressure it will be the one that suspected to pass fuel to can.