F225 analog temp gauge readings

[shoresls1]

I have a new to me 02 wellcraft with an 02 F225.
I've run the boat but did not pay attention to the temp gauge nor the water psi. I was watching the digital gauges. My fault.
It has the dual round digital gauges and a analog Yamaha pro series temp gauge. It also has a water psi gauge. There are no #'s to know what the temp is.

1. what temps do the hash marks on the gauge stand for and what should it run temp wise? On the hose I noticed it creep up to half. I would expect some additional heat on the hose due to lack of water volume but I have no idea what the gauge markings mean temp wise. Also read that the temp buzzer has to be disconnected in order to run this temp gauge? Hmm.

2, the water psi did not move on the hose. Could not tell you if it did when out running on the water. I'm told these f225's are rather low psi?

I've dropped the lower and the impeller looked great.


engine pees solid at idle. no alarms. Then again, I don't have anything to judge it off.

[boscoe99]

Yamaha's modus operandi is to not have absolute values displayed on a temperature gauge. Folks get concerned when they have two motors and see one operating at 145.5 degrees F and the other one operating at 145.8 degrees F. They think the motor running 0.3 degrees hotter than the other motor means that it is defective. They demand that the motor be fixed or replaced.

Absolute values really don't mean much. Just note where the needle normally is on your gauge and use that as a reference value. It might run below normal some days, above normal other days and spot on on some days. It is the nature of the beast. I bet your body temperature is not precisely 98.6000 degrees F every day of your life.

It is completely normal for Yamaha's to have no psi on the pressure gauge when the motor is idling. Most won't indicate anything. The only value specified by Yamaha is that the motor produce 11 psi when it is at wide open throttle.

Best that you can do is to make sure the warning system works. And then, if and when you hear the horn, immediately stop and turn off the motor.

[fairdeal]

FWIW, when Mercury was selling that engine, this was what they printed as a "normal" water pressure -
measured via a Tee in the pisser hose:

[shoresls1]

I guess that's what I'm getting at, I don't know where this engine should/normally does read on that gauge. Does the over temp alarm actually work?

My understanding is that the buzzer does not sound at key ON but only sounds when an actual fault occurs or the lanyard is unplugged and engine is cranked, and it does sound for me when unplugged and the engine started.


however, I do not know if the over heat alarm is intact. I say that because I read that the over heat circuit gets used for the analog gauge sensor. The analog are blue and blk wires on the port top cyl. I pulled them to confirm the gauge movement.

not sure how to confirm over heat alarm works.