the gold screen is for equalizing the diaphragm flexing under the action of the pulses no fuel should exit the screen . Before digging in to deeply have you tried another pump ??
fuel in the pulse line may be accumulated fuel oil mix due to improprer crankcase drainage by the purge valve. if you have the manual see the section of purge valve cleaning
some engines model have a crankcase drain hole in the left channel and no drain hole in the right side channel it is possible that using the right channel is better for such a conversion . I have a feeling the upper crankcase case cavity drains internally to the left side possibly reducing chance of any fuel-oil mix exiting via the pulse line.
in any event tell us more on your exact modification procedure. all the the ones I did worked fine using B&S, Mikuni and square pumps
btw… clear tubing is great to see things but may harden up fast if not fuel resistant type
It is great for filling wine bottles but for “long term” may as well use the good stuff.
Joining AOMCI has priviledges 🙂
