Zurn flush valve causes sink to run/vibrate

[Dielectricunion]

I'm looking at a flush valve toilet which, when flushed, causes the lav faucet to run and produce some rhythmic vibration. If the valves are off on the faucet, how is this happening? Maybe the flush valve is producing higher pressure than the line, surging back the line pressure so much that it overcomes the seal of the faucet washer?

I have not worked on a lot of flush valves so this is probably an obvious one to the more experienced.

 

[Jeff H Young]

Water hammer issue , you could try a new diaphram I dont work on them much either. it should have an arrestor at the w/c nearby adding one at the lave might give relief, lav cartridge might be worn a new cartridge would probebly stop the running but I doubt thats the actual problem