WOWZERS
haven't heard of one of those in a long time
By "auxillary" filter do you mean the secondary?
Look for the return line fron eng to tank and disconnect and place in bucket.... fill both fuel filters and start---watch the return fuel and when the fuel covers the bottom, have someone hold the line down in the fuel and watch for bubbles...there should be none even when run at high idle/wide open in neutral---no worries you can throttle up to full no load speed and do no engine damage
It will no doubt sputter til it picks up a solid delivery of fuel so be patient
Trace the lines from the tank pickup to the first filter [primary] unless yours are mounted in tandem ---been a few years......disconnect line from tank to filter and get a gallon jug filled with fuel and place hose in jug that will reach close to bottom of jug----place jug on top of the eng/fender and run the same way as above...
If the bubbles dissapear, your fuel [lift] pump has bad seals....if memory serves, a rebuilt one is about $150.
By doing this, you are placing the fuel supply above the eng and eliminating the "suction" and basically creating a syphon effect.
Also, be sure and check the fittings at the primary filter head as awell as the main suction line for chaffing/loose fittings as these will also cause suction break.
Also check the shut down lever on top of the govenor---lever opposite the one with throttle linkage---make sure it has no tension on it when shut down...regardless of cable operated or air/electric solenoid...
Good luck and hope this is of some help