2000 Yamaha ox66 stalls at 1100 rpms

[Maybe Later]

I have a 2000 Yamaha 150 Fuel Injected outboard (ox66) that stalls at low rpms. In the water it will not go above 1100 rpms in gear and 3000 out of gear. It cuts off immediatly but will restart right away once put in neutral.

History,
motor has had overheating buzzer sound intermittently at high rpms, reduce rpms and buzzer goes away. recently boat sat for a month without use when it generally gets used weekly. used boat last week and buzzer sounded again at low rpms. used trolling motor to get back to dock. I removed the heads and found that the passages were clogged, cleaned and replaced heads. Buzzer still sounded when I turned the key on. Checked the engine oil reservoir and noticed that it was low. Found that the remote pump that pumps the oil from the remote tank to the engine reservoir wiring was bad. Replaced the pump and fixed the wiring(had to bypass the plug) and the buzzer went away. Took the boat out and I now have the current problem with stalling. Here is what I have checked so far,

Compression = good
Fuel pumps = good
Fuel Filer = good / clean (replaced)
Drained VST housing and gas was clean (replaced VST pump)
Cleaned and tested engine mounted tank sensor
Ran motor on external fuel tank with same results
All cylinders have spark
will not rev above 3000 rpms on hose with out sputtering and cutting out.

Could I have done anything that would have caused this when I fixed the following?

Cleaned and replaced head gaskets?
Re-wired remote oil tank pump by bypassing plug? (are there any resistors in the plug)


Any ideas that might help me out? Need to go fishing!!!!

 

[Maybe Later]

Re: 2000 Yamaha ox66 stalls at 1100 rpms

Rodbolt could I get your opinion?

 

[rodbolt]

Re: 2000 Yamaha ox66 stalls at 1100 rpms

yes you can.
buy or borrow a diagnoistic test lemp, buy or borrow a fuel rail test gauge.
if compression is good and spark is good and the rail shows 35PSI at the failure RPM and code 1 is showing, clean the injector filters.
your splatter gunning things cause you dont seem to know how the various subsystems work.
methinks your confuzziling your alarm indicates.
you sure you replaced the VST pump? its rather pricey.
no resistors.
could you have fubared?
possibly but it sounds like this engine doesnt see proffesional periodic maint.
to resolve your issue will require you to read and rent some special tools.

 

[Maybe Later]

Re: 2000 Yamaha ox66 stalls at 1100 rpms

Thanks for the response redbolt, You are correct I do not know how the subsystems work on this engine yet, but I am learning due to reading all the forums (I am more familiar with old looper omc's a much simipler engine). How much would it cost to get the right equipment? Where can I get it? I have a local outboard mechanic that comes by to work on the engine when there is a problem or when a tune-up is needed (yearly). He does not have the yamaha equipment to diagnose this engine so we have been just going through the basics. We replaced the VST pump on recommendation by a yamaha mechanic (it was $400 bucks sold at his cost). The fuel injectors are going to be cleaned and flowed Monday since it has never been done to this engine. I dont think this will fix the problem since all of the filters (havent checked the injector filters yet) were clean. If this does not fix the problem I am going to take it a licensed Yamaha mechanic to be fixed. I will post back once this is fixed to let everyone know what the problem was.

 

[rodbolt]

Re: 2000 Yamaha ox66 stalls at 1100 rpms

no such thing as a licensed yamaha tech.
however look on the techs wall for a minimum of electrical and fuel systems certifications.
5 star is wonderful but meaningless to a tech. its a video course designed for a begginer.
a better dealer will have at least 1 master tech cert from yamaha on the wall.
the alarm tone is identical for ALL alarms on a yamaha.
the tach visual indicates are what is different.
anything,other than water detect,that setts an alarm also sets RPM reduction.low speed alarms are usually a weak pump or a bad pressure control valve grommet.
intermittant at high speed is usually a clogged or restricted oil filter or line at the remote tank.
once you get that aluminium hot enough to set the overheat it takes 10 to 20 min to cool it back down enough to turn off the temp switch.
but its basic engine,check rail pressure,check spark,test compression, fix the fuel system.
not the first oil harness connector I have cut out and hardwired.
salt water is nasty stuff.
your engine is a basic closed loop EFI 2.6L v6.
all the sensors can be tested with an ohm meter.
and the correct yamaha service manual.
its just faster with the diagnostic test lamp. usually it shows code 1,normal, and allows me not to chase ghosts or the easter bunny.

 

[Maybe Later]

Re: 2000 Yamaha ox66 stalls at 1100 rpms

Injectors are fine as I suspected. I think it is electrical. I'm going to take it to a master tech. I'll post back with the fix.

 

[Maybe Later]

Re: 2000 Yamaha ox66 stalls at 1100 rpms

Borrowed a winki blinkie from a friend and it flashed code 14 which I was told was the crank position sensor. I replaced the sensor and it still did not fix the problem. I have been having trouble with the throttle not wanting to go into neutral with out being real careful. could the throttle control box have something to do with my problem?

 

[Maybe Later]

Re: 2000 Yamaha ox66 stalls at 1100 rpms

Thanks for all the help. I found out that the mechanic that cleaned the passages on the heads pinched the crank position sensor wires when he reinstalled the heads. Fixed the wiring and everything is fine now. Just wanted to let you know what happened.

 

[robert graham]

Re: 2000 Yamaha ox66 stalls at 1100 rpms

Those pinched wires cost you a lot of time and money but in the process you've learned a lot about your motor and that's a good thing! Good Luck!