# Diagnose the problem with my Yamaha (Video)



## sjrobin

A good tech will find it fast, but if you want to shade tree, remove the cowling, start the engine on hose or in water where you can access then with engine at fast idle and using gloves pull then replace one plug wire at a time and note any change in engine firing to determine if plugs are getting voltage from coils or use voltmeter. If firing is good, jump low oil pressure switch or check voltage at low oil pressure switch to check for bad switch. Fuel system is good but check fuel pump diaphragm on engine for damage to ensure good flow to carbs. If electrical is good, pull lower carb and inspect for corrosion. If corroded rebuild all carbs. Last but not least twelve years in the hypersaline Laguna Madre is a long time even for Yamaha. How many hours and do you run the fuel out of the carbs on long storage intervals? How is the boat stored? In sling or indoors? Also de-carbon the cylinders once per year with a fogging solvent to prevent carbon build up and higher operating temps at the cylinder wall.


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## RunningOnEmpty

Is that the HPDI? Those things are complicated.


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## Surffshr

Nah. Just regular carbureted 2 stroke bliss.


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## RunningOnEmpty

I wish mine was that simple!


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## RunningOnEmpty

This is a common problem, but I don't even know if the carbed motors have this ?


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## Surffshr

How many hours and do you run the fuel out of the carbs on long storage intervals? Unknown hours as I didn’t install an hour meter when I repowered in 2010 with this engine. The engine was NIB at that time. The boat hasn’t gone more than a month without being run, but I don’t run the carbs dry on this engine (no quick release fuel line)

How is the boat stored? In sling or indoors? Sling

I’ll get a few of your other suggestions looked at. I’m pretty much DIY on this boat, but this particular issue has me miffed.


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## sjrobin

I like your tenacity. Let us know what you find.


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## RunningOnEmpty

I'm guessing it's still going into safe/limp mode?


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## RunningOnEmpty

I don't see a neutral switch on your carbed model http://www.boats.net/parts/search/Yamaha/Outboard/2006 and Later/V150TLR/CONTROL/parts.html


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## predacious

Surffshr said:


> ‘06 150 VMax. Has run fantastic up until this fall when I had a issue with the gear pump in the oil reservoir. It never came close to running out, but did sound the alarm and go into safe mode. Soon afterward it would intermittently do what I thought was the same thing, but then recover and run fine. Since January it has consistently had the issue of losing power at 2500 RPM and then varying between 1400-2200 after that. I won’t get on plane and this pattern happens like clock work. Otherwise the motor starts, idles, revs(without load), and does what one would expect until it is go time. No alarms or warning lights other than the oil light illuminates when I turn the key on and start engine.
> 
> Anyhow, I went through the fuel system and all is clean and replaced. I found nothing to indicate water in the fuel or some other (obvious) fuel issue. Fuel line are less than a year old and are ethanol rated. I haven’t run any ethanol fuel in it since replacing them anyhow.
> 
> I suspect this issue is electrical simply because it is so consistent, and the timing of it after it went into safe mode. I almost think it needs to be reset, or flashed but this engine doesn’t have the chips of the new ones. Anyhow. All suggestions welcome. I’ll be hauling this video around to local techs soon and thought some other ideas may help me out.



"gear pump in oil reservoir" ?? you mean the oil feed,in the remote tank ?


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## Vertigo

Check the sensor in the engine mounted oil tank. If it's stuck or loose, it will cause the motor to go into safety mode and reduce rpm to about 2000.


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## Surffshr

predacious said:


> "gear pump in oil reservoir" ?? you mean the oil feed,in the remote tank ?


Yes sir. The pump on the bottom of the remote tank went out. It has been replaced, and now keeps the engine mounted tank full as it should.


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## Guest

I have had the thermal switches in the head cause this a few times. Switch makes contact just long enough to throw into rpm reduction but doesn’t sound the horn. Switches tested good on the bench too. First one really whooped me! If it continues to happen, I’d throw a thermal switch at it. I normally do not condone parts swapping without a reason but have seen those switches do funny stuff.


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## predacious

Boatbrains said:


> I have had the thermal switches in the head cause this a few times. Switch makes contact just long enough to throw into rpm reduction but doesn’t sound the horn. Switches tested good on the bench too. First one really whooped me! If it continues to happen, I’d throw a thermal switch at it. I normally do not condone parts swapping without a reason but have seen those switches do funny stuff.



thermal switch ? i'm guessing you mean the temp sensor for the alarm,one in each cylinder head...

if it was an overheat,the alarm horn would be going off,provided the horn is operational - when ignition is turned on,the warning horn would sound.

if the temp is verified,via touching the heads,or infra read sensor,and it's not hot,and the sensor has set,meaning it's tripped,allowing the pink wire to become grounded,the warning horn would be tripped and the motor would fall into "limp mode" - disconnecting the sensor,one at a time,while the horn is going off,this would determine which sensor is bad...

i'm offering no advice on this problem - I would need to see the motor,anything is a guess,i'm not a guesser,i diagnose...


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## Guest

You are correct, the system should sound the alarm if overheating. Yamaha calls the “temp sensor” a thermal switch last I knew. If the thermal switch only makes contact for a very short moment it triggers rpm reduction without sounding the horn. Again, I have seen it happen on more than one engine. You are also correct in disconnecting the pink wire one at a time to eliminate the problem. I too don’t guess, I have spent many weeks i Kennesaw Ga learning a thing or two about Yamaha systems myself. Was only trying to help.


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## Surffshr

Well. The update I have is that I cannot make the alarm sound at all, but the oil light will illuminate. Tested by pulling sensors and cycling the ignition switch. 

1. Pull remote oil tank sensor, no light no buzzer.

2. With remote tank pulled, pull main tank sensors. Red oil light, no buzzer. 

Reinstall all, cycle ignition. 

3. Pull main tank sensor with remote tank sensor installed, red oil light no buzzer. 

Now idk what this has to do with it staying in safe mode, but I am reading that there is not a kill switch to prevent you from running out of oil. 

Anyhow, I’m gonna pull the remote tank and try and test that sensor, the main tank sensor, and control unit? Looks like those tests are possible with a multimeter(but might be tough on the lift).


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## Guest

Have you verified that the horn is operational? Just ground pink wire on back of one cyl head and horn should sound. Also, have you tried my suggestion on the thermal switches? Again, I know it sounds goofy, but have seen it.


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## Surffshr

Boatbrains said:


> Have you verified that the horn is operational? Just ground pink wire on back of one cyl head and horn should sound. Also, have you tried my suggestion on the thermal switches? Again, I know it sounds goofy, but have seen it.


Ground pink wires coming from the thermal switches correct?


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## Smackdaddy53

I have not read the other advice but a few things to check:
Fuel lines leaking/sucking air, primer bulb position and check valve operational (bulb should not suck down when acceterating and should not get soft)
Tank vent
Spark plug wires/boots (a pinhole can jump spark and make it lose top end)


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## Guest

Surffshr said:


> Ground pink wires coming from the thermal switches correct?


Yes, on engine harness side. Just disconnect and touch to ground. You may need a small jumper wire to make contact. If grounded, key on, horn should sound. To test my thermal switch theory, just unplug one of the thermals and try to run it. If it still won’t jump up, plug that one back in and try the other side.


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## Guest

I have also seen evinrude/ johnson power packs/ cdi’s stuck in s.l.o.w/ rpm reduction. I’ve never personally seen this with a Yamaha though.


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## Surffshr

I keep looking for a tiny little pinhole button that hard resets my motor to last year pre-Harvey...errr resets the safe mode... I could use it for this and a lot more!


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## Smackdaddy53

Yours sounds a lot like it’s in limp mode, check your oil reservoir float etc.
I watched this video again and thought of the 90 Mercury I used to have. It would run fine on the hose, crank up and idle fine after launching but under load it would bog down. I took the cowling off one day and had my buddy hit the throttle while we were in the water so I could watch the motor. As he was giving it throttle in gear I was running my hand behind the plugs and the bottom one lit me up from about 1” away. I got back around where I could see it better and when he hit the throttle I could see the bottom spark plug boot jumping spark to the block. I pulled the plug wire off and disconnected the other end from the coil and there was a tiny dark spot on the boot with a pinhole in it where the spark was able to jump out. It would only do it under load. I replaced the whole wire and didn’t have that problem again but plenty others. I hated that motor.


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## Guest

Judging from his rpms, it is in rpm reduction.


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## Guest

Surffshr, did you ever get this figured out?


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## Smackdaddy53

I hate dead end threads. I hope he got it fixed and has been fishing so much he has no time to reply!


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## Surffshr

I’ve spent some time running through things listed and have a few more to do. I’m at the point of pulling carbs for a cleaning and testing fuel pumps for leaks. The alarm wasn’t working due to the horn being out and the rest of the oil system checked out. The part came in to fix the horn so I will do that tomorrow after work as well as pulling the carbs. I plan to soak them in chemtool and blow them out good first. If that doesn’t work, I’ll get rebuild kits for them.


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## Smackdaddy53

Surffshr said:


> I’ve spent some time running through things listed and have a few more to do. I’m at the point of pulling carbs for a cleaning and testing fuel pumps for leaks. The alarm wasn’t working due to the horn being out and the rest of the oil system checked out. The part came in to fix the horn so I will do that tomorrow after work as well as pulling the carbs. I plan to soak them in chemtool and blow them out good first. If that doesn’t work, I’ll get rebuild kits for them.


Solid plan!


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## predacious

Surffshr said:


> I’ve spent some time running through things listed and have a few more to do. I’m at the point of pulling carbs for a cleaning and testing fuel pumps for leaks. The alarm wasn’t working due to the horn being out and the rest of the oil system checked out. The part came in to fix the horn so I will do that tomorrow after work as well as pulling the carbs. I plan to soak them in chemtool and blow them out good first. If that doesn’t work, I’ll get rebuild kits for them.



here's some advice:

find a qualified,i know it's difficult in florida,repair facility.you're grasping at straws,as well as wasting money and time.

problems require diagnosing,not throwing parts and attempting something...asking for advice,on the internet,you'll get the usual keyboard mechanics telling you it's fuel and to use seafoam to fix just about anything.

again,find a qualified repair facility...


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## Guest

Ok then, Surffshr pm me your phone number and the next time you plan to work on it. I will try to give you a ring and walk you through a complete electrical diagnoses provinding you are competent with a multimeter. I assure you I am a competant tech and would check it out at no charge but there are a couple state lines between us.


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## Surffshr

I got everything buttoned up yesterday, including a new buzzer. Now I actually fired the motor up at the ramp and loaded it with very good initial results. Jumped right up to 5k rpm and then backed off back to 1500 or so. Did that several times. So when I got back to the house I remembered the new buzzer. Put it on, turned the key on, and buzzzzzzzz. Went through several cycles of off/on/off, off/on/start/run/off and the buzzer just kept buzzing. No warning light except the oil lamp for 3-4 seconds upon turning key to on then it goes out. Buzzer keeps sounding. 

Did analog tests for both temp sensors which produced a light and different buzz. Pulled main tank sensor and got a light and continued buzz. That light stayed in until turning key off and on which I expect. 

So I really don’t find anything in my manual that would keep a buzzer on with no light, but I’m back to suspecting the oil warning system.


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## Surffshr

So I had a good conversation with @Boatbrains today about how the alarm is always powered and sounds when it gets a ground. I went back through everything and isolated to a pink wire with red stripes coming from the engine that seemed redundant. It was definitely grounding all the time. With it disconnected, both the oil and temp sensors performed as expected. I kept it disconnected and took it out to see how she’d do under load...much better now. 

Kinda hard to pinpoint the issue that caused initial problem. I did clean the carbs up really well, and worked through the fuel system. And I did find an anomaly after replacing the bad alarm (which really could have been me). But whatever. I’ll pick up some fuel tomorrow and get a longer run in tomorrow evening (with rods along). 

Anyhow. I appreciate everyone’s feedback here and Boatbrain takingtime out of his day to give me a shout and answer my questions. Iwas on the struggle bus and dang sure ready to get off of it.


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## Guest

Glad she’s goin, now let’s find what was causing the pink wire to ground. Where did you disconnect it from? As long as thermal switches are still working as well as oil sensor in main tank you should be good. I just like to get all the way to yhe root of the problem. I’m guessing it’s boat side and backfeeding the engine side to do what it is designed to do... Rpm reduction


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## Surffshr

I disconnected at the buzzer at a 3 way plug. There was one yellow 3 way, and one pink 3 way. This wire was part of a 4 wire bundle and not part of the 7 wire bundle that the ignition connects to. I’ll get a pic tomorrow.


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## Smackdaddy53

My low oil level alarm was going off intermittently so I just clipped snd capped the pink wire where it comes out of the top of the oil reservoir. I think the oil level switch is faulty. I just top it off while flushing my motor after a trip and watch the oil level alarm indicator flash on the gauge. It’s better than having intermittent false alarm buzzing.


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