Yamaha VZ225 water pressure ?

[WayneM1946]

Checked my water pressure today and at 2600 RPM the gauge is only showing about 7-8#. Jack Plate was set at 3.5" below pad. Trim all the way down. Does this sound like a normal range or is it low? Never seemed to get hot or give me warning buzzer or anything.

Wayne

[EL Skeeter]

All Yamaha outboards have a minimum water pressure of 11 psi at WOT. There is no water pressure specifications at low or mid range operation.
This is due to Yamaha's High volume, Low pressure cooling system. In fact you may see zero psi at idle as most water pressure sensors start working at 3 psi.

[WayneM1946]

I have not checked it at WOT cause I'm skeered! I have never had my boat up past about 45 MPH. Most of the places I fish are close to where I put in and with trees in the water everywhere.

Wayne

[WayneM1946]

I assumed the water pressure gauge was electric. It ain't. It has a tiny rubber hose connected to the back of the gauge. How on earth do you get an accurate reading on a 1/8" rubber hose traveling 6 or 8 feet from the motor to the gauge. Looks to me like that has trouble written all over it with all the bends and turns that hose has to make. I guess it works, it just seems to me to be sketchy.

Wayne

[yam911]

I assumed the water pressure gauge was electric. It ain't. It has a tiny rubber hose connected to the back of the gauge. How on earth do you get an accurate reading on a 1/8" rubber hose traveling 6 or 8 feet from the motor to the gauge. Looks to me like that has trouble written all over it with all the bends and turns that hose has to make. I guess it works, it just seems to me to be sketchy.

Wayne

Water hitting a tube on the front of the lower unit creates first water pressure and then air pressure within the rubber tube, and air pressure within the gauge. The pressure anywhere within the tube or the gauge is always the same, as long as nothing is changing. The tube could be 50 feet long and have a thousand bends. It would not matter.

For measuring water pressure the system does a pretty good job.

[ifishinxs]

At idle, I get 3 psi in gear and 4 to 5 psi in neutral.

[gmcdaniel1964]

At idle I'm getting about 5 psi and WOT about 23 psi. So I don't think you're too far off of normal.

[Nutoy]

Keep in mind, as the water temp rises, the water pressure will drop.
My WOT water pressure runs 25-30 psi in 60* or cooler water, and 11-13 psi in 85-90* water.