York 92 % eff. Furnace will only start & run when I fill the inducer to trap hose with water. Will run about two to three hour and then shut down on # 3 error ( pressure switch) .Please help!

Sounds to me like it is getting 2 much water into the inducer motor. Is your drain clear? Is your unit a upflow or horizontal?

Is this a 2 stage gas valve, or single? Is the trap box leaking?

Unit is up flow... single stage gas valve.. trap box is not leaking externally . Have re leveled furnace as it was leaning slightly backwards... dropped front by .25 " hope that will help.

I have a york furnace diamond 90 upright. It lights for about three minutes then the flame goes out, then it relites. What could my problem be.