6hp Yamaha only pumps water with muffs on and not in barrel or Sea

[reeflodge]

My last impeller on my 2005 6hp 2 stroke Yamaha disintegrated so I replaced it with a new one and for some reason it pumps water very strongly on the muffs but will not pump at all in a barrel of water or when I took it out to sea today.
Whats going on?

 

[CraigBarnard]

Sounds to me that the impeller is not pumping at all.
When on muffs the water pressure from your hose is doing the work, pushing the water through the system.
Something must not be installed correctly with the impeller.

 

[reeflodge]

But once it is pumping with the muffs fitted and I take the muffs off it carries on pumping really well in the barrel of water!
I fitted a impeller purchased from ebay P/N 6G1-44352-00 is this the correct one?

Its for a 2005 Yamaha 2 stroke engine Model Number 6M8 (European)

 

[reeflodge]

now resolved it was a faulty impellor.

 

[99yam40]

was it the wrong one, or was there a defect in the one you picked up?
was it a yamaha part or aftermarket unit?