Alarm on 150 Yamaha 2 stroke

[Peltz]

Hello, I have a 2004 - 150 HP, 2 cycle, carbureted Yamaha Outboard and had the alarm go off this weekend. I pulled the boat of the garage and started the engine for the first time of the spring using a hose and muffs. I have used muffs a hundred times and never had a problem. After about 10 minutes of running the alarm sounded. The engine was never running at more the an idle except for a few seconds when it was choked at start up. I checked to see if water was pumping and found nothing unusual. The pee stream seemed normal. When the alarm sounded I immediately shut the engine off. Turning the key to the on position, without starting the engine, produced the alarm again. The on-board oil tank was full and the external oil tank was half full.

I believe it was an overheat alarm as the shaft of the motor felt warm. I connected the hose to the hose port near the cowl and let water flush through the system. The water coming out felt warm. A little while later when I turned the key the on position the there was no alarm. The T stats and impeller were changed in August or September 2009. Any thoughts? Should I be concerned or is something that should not be a problem when the outboard is run in the water? Thanks

[BIGDAWG2566]

Hello, I have a 2004 - 150 HP, 2 cycle, carbureted Yamaha Outboard and had the alarm go off this weekend. I pulled the boat of the garage and started the engine for the first time of the spring using a hose and muffs. I have used muffs a hundred times and never had a problem. After about 10 minutes of running the alarm sounded. The engine was never running at more the an idle except for a few seconds when it was choked at start up. I checked to see if water was pumping and found nothing unusual. The pee stream seemed normal. When the alarm sounded I immediately shut the engine off. Turning the key to the on position, without starting the engine, produced the alarm again. The on-board oil tank was full and the external oil tank was half full.

I believe it was an overheat alarm as the shaft of the motor felt warm. I connected the hose to the hose port near the cowl and let water flush through the system. The water coming out felt warm. A little while later when I turned the key the on position the there was no alarm. The T stats and impeller were changed in August or September 2009. Any thoughts? Should I be concerned or is something that should not be a problem when the outboard is run in the water? Thanks

[BIGDAWG2566]

change thermostats

[marshwabbit]

i'll second the thermostat change.

when was the last pump change?

[Capt Rick Hiott]

I have the 2003 model of the same motor. They told me at the dealer that the motor would run hot while on the muffs and not to use them.

I have always flushed mine while using the little hose that comes out of the block that's made to flush the motor with.......................

Remember,,you can test the thermostats your self in a pot of water on the stove with a thermometer,,,,,,,,Before you buy new ones.

I would put the boat in the water and run it before I did anything.

Edited March 25, 2011 by Capt Rick Hiott

[seahorse]

If you were using the round ear muffs, that may have been your problem. The rectangular ear muffs have a better fit over the Yamaha inlet screens. You should also use a dual feed flusher for best results.

The hose on the motor with the garden hose fitting is NOT for running the motor. It is only to have water fill the block and wash it out. Read the owers manual - do not use that hose and run the motor.

[Sans Peur]

Using the hose on the block will destroy the impeller as it ONLY supplies water to the block and nothing to the impeller. You might as well run it without anything.

As to your alarm, Yamaha's are notorious for not liking the muff's. I ran my F250's on the muffs a few times but never for long. I know a Yamaha tech and he advised against it, especially since I was on a well and my pressure and flow was questionable anyway.

[Sidewinder]

Hello, I have a 2004 - 150 HP, 2 cycle, carbureted Yamaha Outboard and had the alarm go off this weekend. I pulled the boat of the garage and started the engine for the first time of the spring using a hose and muffs. I have used muffs a hundred times and never had a problem. After about 10 minutes of running the alarm sounded. The engine was never running at more the an idle except for a few seconds when it was choked at start up. I checked to see if water was pumping and found nothing unusual. The pee stream seemed normal. When the alarm sounded I immediately shut the engine off. Turning the key to the on position, without starting the engine, produced the alarm again. The on-board oil tank was full and the external oil tank was half full.

I believe it was an overheat alarm as the shaft of the motor felt warm. I connected the hose to the hose port near the cowl and let water flush through the system. The water coming out felt warm. A little while later when I turned the key the on position the there was no alarm. The T stats and impeller were changed in August or September 2009. Any thoughts? Should I be concerned or is something that should not be a problem when the outboard is run in the water? Thanks

Could be the muffs. I have a 200HPDI. Alarm went off when I used muffs. Now I use the flush hose on the motor and do not run motor when flushing. I also have used SaltAway since the motor was new. Also have a cattle tank to drop motor in when decarbing or when I take out of storage first part of season, Also connect a hose with running water in the tank to keep it cool. If not water will become to hot.

[Mardi Gras]

My 150 did the same, long hose run and 10 minutes overheat, stuck it in real water and no problems.....

[coolapple]

When using muffs always use the dual feed muffs that allow water in from both sides. As your motor build deposits in the water jacket it will do this over time. I too have a Yamaha that started doing the same, but a quick check of the poppit valve showed why (clogged). Yamaha's also have very picky and tight tolerance setting on the sensors, usually only a degree or two so check that your sensor is not going off early. What I do is just heat some water to the max temp and drop the sensor in while still connected to the motor. Use a good digital thermometer to ensure the temps are spot on.