Alarm on Yamaha 115HP

[pappastratos]

I have a 2000 Yamaha 115HP 2 stroke. I had recently installed waterpump kit, thermostats, cleaned poppit valve, fuel/separator filter. been running without any issue until this weekend. We had ran about 5 miles at 3000-3500rpm. We had slowed to turn around, took off again raised RPM to about 4000RPM to plane off and alarm goes off. I don't have a smart gauge. I tie up to a dock, check oil levels, tank & motor, all OK, motor seemed to be at normal temp?. Checked water pickups on foot. Turn key on, no alarm. Started motor, started back to launch, increased RPM to about 2500, no issues. We rode for about 15 miles like this with no alarm. Motor ran correct. We got back close to launch, I had been increasing RPM, 3000RPM, no alarm, 3500 RPM, no alarm, hit 4000 RPM alarm goes off again. I immediately slowed down, to idle for 10 seconds to get to the side of the side of the river. Turn motor off, 10 seconds later turn key back on, no alarm, starts back up. I once had a temp alarm go off, it took 15+ minutes for the alarm to quit. Could it be a Fuel restriction? Voltage issue? The volt meter on depth finder reads about 12.5V
Thanks in advance

[99yam40]

a good battery just sitting on a shelf should have 12.7 volts,
on a motor with motor running it should be 13.5 or more in my opinion.
and yes low voltage can cause problems
some had a low voltage warning, but I have no idea which ones

[TownsendsFJR1300]

Plus 1 ^^, but check static and charging voltage AT the battery itself, (as well as connections-TAKE off / clean, no just "looks good")...


How much corrosion inside the block did you see with the T stat out, etc? Often, older engines, run in salt water, the head/ cylinder passages clog up with salt. They tend to overheat ONLY at higher RPMs(not enough water flow thru the heads)

[pappastratos]

Thanks, but if it was overheated, the alarm would would not reset until it cooled off. This took 15 seconds to reset

[99yam40]

Thanks, but if it was overheated, the alarm would would not reset until it cooled off. This took 15 seconds to reset

so what does that leave for you to check out

[pappastratos]

so what does that leave for you to check out

Not sure, That is why i am asking on here.

[99yam40]

we both mentioned low voltage.
battery voltage is easy to check to see if the motor is charging properly
good connections are important

[TownsendsFJR1300]

Thanks, but if it was overheated, the alarm would would not reset until it cooled off. This took 15 seconds to reset

When the RPMs lower, there is NOW enough coolant going thru the head to stop the over heat- Higher RPMs produce more heat. If not enough water flows for the heat generated,
it'll overheat.. Blocked water passages can prevent enough water flow..

*AGAIN, rule out your charging system first, repair that if need be..

[pappastratos]

Thanks for info, I will look at my manual to see how to check the charging system. Curious, some time back I did have a over-heat alarm, it took 15+ minutes before the alarm would quit sounding. (Motor not running, turn key on to check) this alarm would reset in 10 seconds. I know oil levels cause an alarm on this year of motor. I will check oil tank wiring too.

[TownsendsFJR1300]

To check the charging system, simply check voltage (with a simple meter) at the battery terminals.

As noted above, above 12.8 volts-not running, battery sitting... When running and PROPERLY charging, should be (generally) at least mid 13 volts up to 14 volts or so...

If you have proper voltage at the battery, check again at the engine where the positive cable connects to the engine. Might want to check grounds(black cable) at both the engine block and battery terminal. A bad connection will not allow the battery to charge nor the engine to draw the power it needs to operate..


Per the low voltage reading at your gauge, there's an issue either there, or elsewhere in the system.

Gotta fix the basic stuff first.


.