1996 Mercury 15 HP Waterpump

[otth2oskier]

I replaced the impeller on my motor. I tested it in a bucket with a cordless drill driving the shaft. It pumps great, lots of flow and pressure. When I reinstalled the lower unit and tested it, there was very little flow, almost none. I am at a loss of what to try. I am quite sure I lined up the tube up to the powerhead properly. Any thoughts?

 

[racerone]

Maybe put more water in your test bucket.------Water must be 6" above the pump.

 

[flyingscott]

How long did you let it run. The thermostat controls the pee hole on that motor.

 

[Sea Rider]

The thermostat controls the pee hole on that motor.

If so, remove thermo, check its current cond, if severely rusted, salt crusted install a new one in.

Happy Boating