Yamaha 90hp 4 stroke water flow problem 2011 F90 TLR

bcomer

Seaman
Joined
Dec 22, 2003
Messages
63
Got this boat on Friday. 5 minutes after putting in water the overheat alarm sounded. Shut motor off. No water coming from pee hole so removed lower end and replaced water pump-entire kit. The impeller had nothing left for vanes. Removed all the broken impeller pieces from pump. Also found a lot of impeller pieces behind the water intake screens on skeg. Cleaned all out. Reassembled pump and re-installed lower end.
No water from pee hole unless running at 1500+ RPM. Motor still sounds overheat alarm.

Checked thermostat--all good. Removed and inspected pressure control valve. Looked okay.

Ran motor with water house connected to flush port. Plenty of water through pee hole and motor does NOT overheat or sound alarm if water is forced through using the flush connection.

Remove flush connection and back to original problem.

This motor has 95 hours on it. What else needs to be checked or could prevent water from properly circulating through the motor? Is there a diagnostic flow chart to troubleshoot such problems?
 

bcomer

Seaman
Joined
Dec 22, 2003
Messages
63
Here is update.

I decided to change the water pump housing just to be sure and noticed that the impeller kit the dealer sold me originally did not see quite right. Turns out the impeller was an 1/8 of an inch shorter than it should have been. Got another kit with right impeller and all is well. A lot of aggravation and a lot of time spent chasing a problem that did not exist except for a wrong replacement part.
 
Top