Proper water pressure for 115 Yamaha

[fishpole63]

Last summer I installed a water pressure gauge for my 92 C115 Yamaha. When I checked it out, I was running about 25 PSI. This led me to discover that I had a faulty thermo sensor as the motor was shutting down with good pressure. Unplugged the sensor, problem went away. Now, for the past two months, water pressure has been eratic at the meter. Reads about 25 to 28 psi when trim under and running about 4500 rpm even in tight corners. But, when opened up and running flat out on the straights, the pressure drops down to about 15 psi, especially when I try to trim out all the way. It acts like the gauge hose is being pinched but I've checked it out thoroughly. Sometime the problem will correct itself and go back to 25 psi. I haven't pushed the issue too much as I'm afraid of burning her up (still got that starboard sensor unhooked). So, two questions. 1) I installed the connection for the water pressure gauge on the port head. Was this the correct side and does that give me a reading for both heads? In other words, if it reads 25 psi, can I be sure that both heads are getting this water flow? 2) At what point should I be concerned about the water pressure? Is 15 psi too low?
Have recently cleaned poppit valve, verified thermostats by removing and checking opening and closing, and replaced the water pump. Adding the water pressure gauge was the last thing I did.

[Sigma]

It does not sound like you have a problem too me. 25 psi trimmed down and 15 wot should be fine.

Port is the correct side.

Water pressure Gage fluctuation could be choppy water or just the thermostat partially opening and closing due to cold water temps of the lakes this time of the year.

I get 25 psi at mid throttle and close to that at wot as well, but my motor is on a tin rig and it sits low in the water.

[fishpole63]

Thanks abu,
Do you know if I can install one of the new mushroom head type poppit valves that are supposed to eliminate some of the clogging problems? Know where I can get one?

[Hamfisted]

Greg you can use the new mushroom headed PVC valve in your '92 motor. They used the same part in all the motors so they are all upgradable. The p/n is 60H-12416-00-00 and you can get one at the dealer for about $5. If your PVC seat seal has never been changed I would get a new one too, maybe even a new spring. Get a new gasket too.


-Mike