# Yamaha 150 has been a problem for awhile



## FLWhaler (Oct 1, 2007)

<P class=MsoNormal style="MARGIN: 0in 0in 0pt">OK here is the scenario. Yamaha 150 late 90?s model. Runs fine at low rpm and no problem starting. Open up and run around 4000 RPMs? and after about a minute an alarm goes off and the motor starts cutting out. Thinking it may have been over heating the impellor has been replaced. The next step was to put a heat gun on it after the alarm goes off. The temp on the heat gun only reads 138 or less. So I?m pretty sure it?s not overheating. Pulled the heat sensors out with same results. What other alarms will cause a Yamaha to start shutting it self down besides over heating and oil alarm and there is oil in both tanks. One other caveat is this is a tunnel hull but it looks like plenty of foot is in the water. <P class=MsoNormal style="MARGIN: 0in 0in 0pt"><P class=MsoNormal style="MARGIN: 0in 0in 0pt"><P class=MsoNormal style="MARGIN: 0in 0in 0pt">HELP any input appreciated.


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## Sequoiha (Sep 28, 2007)

With that year model, its most likely the pressure control valve,,, especiallly with the alarm sounding at higher rpms...


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## outbrdwrench (Apr 8, 2009)

The answer is no. The only things that will cause your motor to give alarm & go into reduction, are overheat& low oil . You say the motor is reading 138 degrees when it goes into reduction. It must either THINK it is overheatingor has low oil in themain oil tank. Start out by Packing the thermoswitches recesses with dialectric grease. They have been known to give false readings if this is not done because of vibration. If this doesn't work, I have plenty of other suggestions. outbrdwrench.


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## wflgator (Oct 1, 2007)

Sounds a lot like the problem I had where the aux oil tank in the bilge was not pumping enough oil into the smaller oiltank mounted inside the engine cowling.The alarmwould come onat high RPM then then engine would override the throttle and reduce overall RPMs. Don't know if you have the same set up or not. Mine was on a 2001 150 2 stroke. If it is a similar set up then check the line going from under the aux oil tank to the smaller tank. I had to blow mine out with some compressed air last fall. Been working fine ever since.


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## MULLET HUNTER (Oct 3, 2007)

their is also a fuel/water alarm on some models that will also cause power reduction.


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## outbrdwrench (Apr 8, 2009)

Not on this model. outbrdwrench.


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## DOUBLE "D" & LV (Oct 2, 2007)

If you have the Yamaha digital gauges, what alarm indicator starts flashing? If you do not have that, then have you pulled the engine oil tank sensor out recently. If so, you may have not lined the filter up and pinched the sensor or blocked the vent hole on the filter. The other thing that could be happening if you haven't pulled that is, sometimes when the engine tank sensor is malfunctioning, it will intermittently short out and give a low oil alarm. You would have to test it with a meter. If the sensor is bad, it will short out when you slightly bend the sensor. I say slightly because if it done too much, you will break the sensor and be replacing it anyway.


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## outbrdwrench (Apr 8, 2009)

VERY good advice David! Pretty slick dude! Not very many people know about the vent hole at the top of sensor strainer, muchless the affects on the sensors accuracy, if it's not aligned properly! I did'nt know if the advice I had given a few days ago had any effect, & was waiting for a report fom him before giving further advice. I have definitly seen this cause the injection alarm to false. At WOTthe sensor strainer can't fill back up with the oil being used fast enough,causing the sensor float to fall below the actual oil level in the tank, itcan confuse the hell out of that sensor if it's not vented properly. again awesome advice David & further proof of you'r extent of knowledge! outbrdwrench.


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## metal11 (Oct 7, 2007)

I'd agree with the above if he as pulled the sensor at some time.I would look for a bad wire also, it may be pinched and causes an alarm when at high rpm's. When you say you removed the sensors did you disconnect the temp sensor after you got the alarm?


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## GREINOLD (Aug 11, 2009)

i CAN'T OFFER HELP BECAUSE I'M LOOKING FOR SOME TOO! MY 1999 C75TLRX YAMAHA TWO STROKE 75 HP ENGINE EXHIBITS ALMOST EXACTLY THE SAME SYMPTOMS. I HAVE REPLACED THE THERMOSTAT AND THE THERMAL SWITCH. BUT THE PROBLEMS PERSISTS. 



AT ANY SPEED OVER 2000 RPM, THE THE ENGINE GOES INTO OVERHEAT MODE WITH BUZZER GOING AND THE SLOW SPEED MODE ENABLED. 



THE ENGINE IS NOT OVERHEATING AS I CAN PLACE MY HAND ON THE ENGINE BLOCK WITH NO ADVERSE EFFECTS, THERE IS A STRONG TELLTALE AND ALL ELSE LOOKS OK.



cAN ANYONE SHED SOME LIGHT AS TO WHAT TO DO NEXT?? HELP!!


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## DOUBLE "D" & LV (Oct 2, 2007)

Check the pink wire in the harness for a pinched or chaffed area. I have seen the wire do that and give false warnings. If you are sure that the engine is not overheating, then unplug the temp sensor and run it. Sometimes the sensor shorts out. When you feel the head for overheating, feel where the sensor is. If it is hot, then the water passage by the sensor is probably clogged and causng a hot spot. Seen that too.


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## jamester (Sep 12, 2009)

Oil alarm problem with my 2001 Yamaha 150HP 2 stroke.

The oil level indicator flashes most of the time even though the reserve tank up on the engine is full. Then some times it does not flash but shows the tank to be full. When I travel at high speed and use up all the oil in the reserve tank, the alarm goes off and the engine goes to low speed just as it is supposed to. I must then use the switch on the engine to fill up the reserve tank. Some times I can fix the flashing low oil level signal by simply turning off the engine and restarting it. This does not always work however. The problem is there most of the time but fixes itself once in a while. We had the level sensor within the reserve tank changed and this did not help. Any suggestions on how to correct this problem? Has been happening for a number of years with no solution. Bad electrical connection in a connector??? Defective engine computer that fails intermittently?? HELP!!!!


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## DOUBLE "D" & LV (Oct 2, 2007)

Replace the clogged oil filter on the boat tank. If that does not fix it, then check the power supply going to the oil pump and see if it has battery voltage. If it does, then you may have a bad oil transfer module. Have you listenned for the oil pump on the boat tank to come on if the engine tank is down below the bottom line? (you can check that if you drain the engine tank by pulling the drain tube off at the bottom then turn the key on when the oil is 1/2" below the bottom line. Be sure to put the drain tube back on when you reach this level and tie strap it back on.)


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## sosmarine (Sep 28, 2007)

jamester PM sent


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## baymotorsports (Feb 28, 2008)

my problem.....

pretty similar, i have twin 1995 150 salt water series motors, both start/idle/run well, nice pee stream from both, but when i go over 5k rpm the starboard motor will give a alarm, will NOT reduce power, but will sound the alarm, i can back it down to 3k or so rpm and it goes off in about 10 seconds, i was thinking possibly the poppet valves or thermos need to be replaced,

any ideas?

also i have noticed every now and then i can look at the gauge and its got the indicator flashing on all 3 oil marks, 

i read the book and it doesnt mention all three flashing, it says the full and empty mark will flash if there is a clog but again doenst mention all 3 flashing, what does this mean?

thanks


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## DOUBLE "D" & LV (Oct 2, 2007)

I would replace the boat oil tank filter first.


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