I just recently bought a boat with a Yamaha outboard 200hp VMAX 1998, the owner said the water pump did work and it seems as its not working as it should, just a very low pressure stream out of telltale and also no pressure on Gauge, also no difference if on WOT or idling, is the impeller bad and should i just replace the impeller or also the insert, housing, etc... because the engine does overheat after running for about 2 min with the flusher hose attached. Any help appreciated.
Replace everything with a kit can’t go wrong
Don't ignore the thermostats and pressure control valve.
1990 Ranger 362V Yamaha Pro-V 150
Old Town Predator MinnKota
Make sure to change poppet valve also. As mentioned buy the water pump kit so all is new. Had same problem with my 99 Vmax
EAsy insurance to go ahead and change the items mentioned above. When you go to change the thermostats, you can test the old ones with a pot of boiling water to confirm they are working. Also, blow through the rubber tubing to see if there are obstructions.
might as well change the lower unit oil as well to make sure there are no leaks in the seals.
I had one and poppet at rear of engine was always issue, rocks sand and everything else built up there
Ron Fears
Stroker/300XS
1E003823
As with the above the poppet valve could be stuck open with debris. Check that first. If it's continually open it will have low water pressure.
First off if your running it on the hose take off the plastic scoops since they prevent full water flow getting into the channel that feeds the water pump. Not many O/Bs show much pressure at idle but at full rpms you should see 12
to 20 depending on engine height settings and rpms. I would do a complete kit find the small hos e that feeds gauge and see if it’s blocked. Thermostats control temps to make it burn more efficiently. The popped valve opens at about 2,200 rpms give or take they get dirt build up on them over the years, clean or replace and reseal.
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