I have a power washer with a honda GC 190 6.5 horse on it that no longer runs correctly. It will start and idle but it pours black smoke when doing so. When i press the trigger on the gun i only get full pressure for a half second before the engine seems to die down and then it revs up again and does this in a cycle until u let go of the trigger. i changed the engine oil with no change but have not changed the pump oil. Any idea why this is happening and any suggestions on how it could be fixed ?

Hi , I Would Adjust/clean The Carb First If It Still Doing The Same Thing , A Carb Rebuild Kit Is In Order.

Sounds like a carb issue, clean/adjust or carb kit.
Dean