Force Cooling/ no Pick up- Not cooling 50hp

This is my third boat all others have been i.o.'s.

I've changed the powerhead on this 50hp Force (507Y8D) because of a melt down. After tearing it apart, it's back running again, but it still has the same cooling issue. There's only exhaust out the pee tube.
I was told the impeller is new, & after inspecting it it doesn't look worn. The water pump housing looks grooved a little, but should still work. The copper pickup pipe went back together fine & sits in the bottom of the powerhead correctly.
1st test I removed the lower unit with engine off, I flushed water throught the copper tube, and that flows perfectly. 2nd test lower unit in a barrel of water & spun the shaft by hand to get some water to flow out the water pump spout. When all together it works with the muffs, yet in the barrell nothing.
- I have the manual & read many other threads. Sorry about the length of my woes.

Re: Force Cooling/ no Pick up- Not cooling 50hp

Set deep enough in the barrel?

Re: Force Cooling/ no Pick up- Not cooling 50hp

+1 what Foodfisher said. Water level needs to be up above where the water pump sits.

Re: Force Cooling/ no Pick up- Not cooling 50hp

Check the water route for any blockages (sand, etc)?

Edit...never mind I just saw that it works on muffs. +1 to what the other guys said , probably not low enough in the barrel.

Re: Force Cooling/ no Pick up- Not cooling 50hp

Being cute. you could cut the side of the barrel to lower the motor or add more water.

Re: Force Cooling/ no Pick up- Not cooling 50hp

change your impeller. i had just had a guy bring over a force 125 and it had no water flow i had taken the impeller out and looked good but a little rough on a few edges, i changed it anyway and it solved the problem. also did you check your thermostat?

Re: Force Cooling/ no Pick up- Not cooling 50hp

i just rered the post and if it worked with muffs on i am still sticking to impeller cuz when the muffs are on you have pressureized water flowing in and in a barrel you don't and the water pressure is enough to get it to flow threw.