The alarm buzzer in the throttle/control box of my engine (2 stroke 50hp 3cyl 1999 yamaha) started going off last time out. Checked the oil level was full and the telltale was strong and cool. Took boat for service. Impellor replaced, thermostat checked and cooling water pipes blown out and checked. Engine then started and sounded fine. Went out yesterday and after running for 5 mins the alarm came on again. Tapped the control box a few times and the alarm spluttered a bit. I assumed it was thus a short somewhere. Ran the engine whole day and ran perfectly. On the way home the alarm, which had been on most of the day, suddenly went off and stayed off. Could there be an electrical short somewhere or is this a more serious problem?any help will be greatly appreciated.
You did not say if it was trailered when it went off. If so, you still have an overheat problem. Did you chedck thermostat? If not, it may be stuck 1/2 open. Does it stay on when the motors off? Did you check the oil pickup in the injection tank? If you sent this to a shop with the problems and it still has it, take it back.
Thanks for the reply Thom. When i started the engine and it was idling, there was no buzzer. After running for a minute or so at 3/4 throttle, the buzzer came on. If i turned the engine off and let it stand for 20 minutes and then restarted, the buzzer was off until i started running fast again. The thermostat was checked and tested and operated correctly. If i turn the motor off and then immediately turn the ignition key to the on position, the buzzer is still on.I have not checked the oil pickup (how do i do this?) but the engine is consuming oil as the oil level is going down at a similar rate to the other engine.Any other thoughts. How can i be sure that the problem is electrical or a sensor and that the engine is not actually overheating?
This is similar to a problem that has been bugging me with my motor, which is a Yam 40hp 2 cyl. I tried everything to get the problem sorted out.I started with a new thermostat, then a new thermo swith, then an impeller. I then convinced myself that a motor may have been blocked by salt so I bought a Saltaway kit. I then read on this board a post from a guy who needed 2 new thermo switches to cure his problem as his first new one was also faulty.I bought a 2nd new one and the buzzer then only came on at much higher revs. I continued to flush with saltaway just in case. I then ran the outboard with the old thermoswitch to see what happened. I ran at 30 mins at full throttle with no buzzer. I then realised that I hadn't connected the old one properly as one wire was hanging loose. I then knew conclusively that my motor was not really overheating by this stage (Obviuosly not recommended!). I put the new one in making sure the connection was good and was still able to run at full throttle no problem. I doubled checked my thermoswitch was connected right by unscrewing it from the block and heating with a cigarette lighter with the ignition on. For me I think the 2nd thermoswitch definitely solved my problem. My first new one was supposed to have been fitted by the mechanic but maybe he didn't bother. The saltaway may have helped but I'm not convinced of this. Maybe running at max revs increased water pressure and helped clear the water channels. Not sure about this.One useful thing I read here was that it is possible to connect the buzzer directly to the thermoswitch at the engine so you can eliminate any potential shorts or problems with the wiring loom. I am not sure how to do this though. This is what I was planning to do next. Hopefully my problem is sorted for good as it drove me insane for 3 years.Buy a new thermoswitch and see what happens.Good luck and let us know how you get on.CheersAndy
Thanks AndyDoes indeed sound very similar to my problem. I have taken the engine back to the dealer and after testing everything he believes the buzzer itself is faulty. He says he has tested it with a new buzzer and it would appear that all is ok. I will reserve comment until i have had the boat out on the water again. If this does not solve the problem then i am sure it will be the thermoswitch. Many thanksJacques
JacquesThat is an interesting diagnosis. The temp rising (to > 100 degrees c. according to Yam UK ) gives continuity, ie a complete circut at the thermoswitch, which then activates the buzzer. The buzzer shouldn't be getting any current till the thermoswitch provides it so is a passive link in the chain. See what happens. If the new buzzer doesn't sort it the thermoswitch will be the culprit.
Thanks Andy. Will test this weekend and let you know the outcome. The dealer assures me that they ran the engine extensivley with the new buzzer fitted and the problem seems to be solved. Perhaps there is some difference in the wiring setup? Anyway, as you have pointed out the problemn is now either the buzzer or the thermoswitch and can be solved easily.Thanks.
Yamaha 50 3-cyl (1999) - alarm buzzer
Linear Mode
