Yamaha 60hp 4 stroke FI Miss / stutter

[Bigtime57]

I have a 06 T60 Yamaha 4 Stroke FI that has started Missing / Stuttering when you have the boat on throttle cruising the lake it all of a sudden just falls on its face.... idle drops starts missing with the throttle still in the same position.....you can drop the throttle back and try to speed up and it misses even worse.... no warning given it just runs perfect then all of a sudden just stalls.....I have noticed this weekend that if you shut it off and turn it right back on its perfect..smooth as silk.... might go 20-30 min or longer and same thing again....i have ran injector cleaner and sea foam with no difference....... motor runs perfect like day one from the factory until it decides to stall out........has me totally stumped.

[dark_star]

Is there a water/fuel separator ?
If not could there be water in your fuel ?

[99yam40]

Monitoring fuel pressures when this happens would tell if that was a problem.
if pressures are in spec, then look for injector or spark problems.

do you have gauges that tell if overheat or low oil pressure shows a problem?

are you sure you alarm system functions as it should?( buzzer and lights)

[TownsendsFJR1300]

Sounds like a crappy connection inside the ignition switch killing the engine.

When it fails, do you loose all power (to the gauges, fuel level, etc,) as if the key was turned OFF?


If so, try spraying some electrical contact cleaner down the ignition switch (and let dry while working the key back and forth-battery DISONNECTED).

[Bigtime57]

Is there a water/fuel separator ?
If not could there be water in your fuel ?

we have drained all fuel , installed new fuel filter, low pressure pump, new plugs

[Bigtime57]

after replacing the filter, fuel, low pump & plugs we took the boat out yesterday and soon as we passed the wake zone with the throttle set a 5000 rpm ran perfect for about 15 min then bogged down...all gauges still full power with no changes..... i dropped the throttle back to neutral and increased the throttle again and stuttering and no power hardly....shut off the engine restarted it and ran perfect for about 30 min then did the same thing again...... its almost like the motor is going into "Limp" or "Protection" mode..... since you can shut it off and restart it and it works fine..... but I have no alarms at all going off....and to be honest I have never heard alarms on my boat.... and i am the second owner of my 06 Bennington Pontoon with the boat/motor/trailer was all bought brand new.....everyone ask me about the alarms going off but never heard any .......

[99yam40]

may be time to test your alarm system to see if it works and the gauges indicate what is setting the alarm.

monitoring fuel pressure when the problem shows up will help tell if the fuel pressure is a problem

[TownsendsFJR1300]

That, ^^^, and hook up to YDIS...

Agreed, sounds like an engine "safety shut down" as the re-start works fine..

[pstephens46]

If you remove the safety lanyard and try to crank motor, the audible alarm should sound.

[Bigtime57]

If you remove the safety lanyard and try to crank motor, the audible alarm should sound.

i tried this last night and motor started but no sound with lanyard off........ any idea where the alarm should be located on the boat and what wires should be attached the lanyard mounting plate? This boat is very well maintained and all the wiring is tip top shape so kinda shocked me that the alarm didnt go off...so not sure where to start looking but figure its close to the throttle/key area

[pstephens46]

i tried this last night and motor started but no sound with lanyard off........ any idea where the alarm should be located on the boat and what wires should be attached the lanyard mounting plate? This boat is very well maintained and all the wiring is tip top shape so kinda shocked me that the alarm didnt go off...so not sure where to start looking but figure its close to the throttle/key area

I believe location depends on the type of throttle control box that you have.

[TownsendsFJR1300]

Heck, with the lanyard pulled off the ignition switch, the engine should have lost spark and NOT started...

[99yam40]

very true and if the kill switch does not ground out the spark voltage the ECU would not know to sound the alarm.
at least that is how I think it works

[Bigtime57]

very true and if the kill switch does not ground out the spark voltage the ECU would not know to sound the alarm.
at least that is how I think it works

this has told me alot so i at least know i need to start there at the controls ......and work from there ..... so i have alarms more than likely just something has them shut off

[99yam40]

normally the buzzer gets 12V+ at key on and then the buzzer is set to make noise when the negative is grounded.
I am not sure what grounds it on you F60.
ECU or temp and oil devices

with ECUs I would think everything would go to the ECU and that brain decides what to do with that info.