Yamaha OX66 Mystery Alarm

[cousinabe]

I have twin 2000 Yamaha 200's on Parker 2520 Pilothouse.....both engines start and run great, however, if I run 4200 RPM's plus for any amount of time the alarm (solid tone) goes off on port engine. Not sure if the alarm is an over heat because the whole gauge is flashing (no Red). I shut the engine down for 5 minutes and it is good to go if I keep it below 4200 rpm's.
The engine does not go into RPM reduction mode.

I take the engines down after hearing the alarm, they dont shut down or reduce RPM's at all. That said, its only a few secs from when I hear the alarm until i shut down the port engine.

The impellers were changed this spring. I cleaned the poppit valve which was not clogged. Will be changing the t-stats soon.

Does anyone have any suggestions ?
VST filter? O2 sensor?

thanks for your help !

 

[Ray Neudecker]

Re: Yamaha OX66 Mystery Alarm

First I would check all of the battery connections at both ends.

 

[rodbolt]

Re: Yamaha OX66 Mystery Alarm

what Ray says, i9f the entire guage is flashing it could be a guage malfunction or the loose battery alarm.
if that motor sees a voltage drop or spikes it will alarm.

 

[cousinabe]

Re: Yamaha OX66 Mystery Alarm

I am investigating this problem for a friend.
I took his boat out and ran it at 4800 rpm's
1) Alarm sounds, no flashing of any indicators, just the alarm buzzer sounding.
2) Both motors go into reduction mode.
3) after a restart, the buzzer would come on as soon as the key was turned from the off position. port engine.

Battery cables were solid and well connected. Isolated motors to ALL, 1, and 2 batteries. Symptom still occurred. If we ran the boat at 3600 rpm, all was fine. once we got over 3800 rpms, the alarm would eventually sound and go into reduction mode.

thanks for any assistance.

 

[rodbolt]

Re: Yamaha OX66 Mystery Alarm

have you physically felt the heads or looked at the oil level on the engine tank?
your eyes are the best test device ever designed.
your describing either an overheat due to internal scale or obstructions or slow oil transfer. however low battery voltage can set it as well and if one engine goes into RPM reduction they both do.
thats a function of the DES switch on the back of the ign panel.

 

[cousinabe]

Re: Yamaha OX66 Mystery Alarm

how come no flashing occurs? just the alarm?
could this be a fuel restricition?
thanks

 

[rodbolt]

Re: Yamaha OX66 Mystery Alarm

beats me.
how come you have not tested the visual indicates ? unless someone added some kind of switch Yamaha ran no fuel alarms.
if you unplug the remote oil tank with key on engine off you should get a remote low indicate, with the remote still unplugged drain the oil from the engine tank until the low oil alarm goes off and the visual swtches from remote low to engine low.
plug the remote back up and it should refill within 180 seconds.
you may have to cycle the key.
with key on engine off take one of the pink temp switches to ground and if the tach has a visual it and the audible should be set. if the tach does not have the visual the speedo should.

 

[cousinabe]

Re: Yamaha OX66 Mystery Alarm

we ended up cleaning out the remote oil tanks for each engine. i physically removed them, took off the small filter and cleaned out any sludge with carb cleaner.
so far, no alarms have gone off in the last 20hrs of use.
this seems to have solved the problem.

 

[HJohnson]

Re: Yamaha OX66 Mystery Alarm

Just got on here and not sure how to ask for help on a thread(?) but here goes: i have a '99 Yamaha 200 ox66 EFI saltwater series II, when i get uo on plane and the rpm's sre over 3200 it will run for about 90 seconds, buzzer comes on, temp light comes on and rpms decrease, I checked the head temps with an infrared heat detector and all temps on both heads are normal; put in two new thermostats and sensors, inside water jacket looked great-no scale or corrosion buildup at all, ran it, same problem, unplugged pink wires and narrowed it down to starboard head, swapped sensors, still came back, starboard head, can leave pink wire off sensor for starboard head and runs fine- no alarm; constantly checking temps both heads, nothing ever over 134 F... any suggestions as to where to go from here?

 

[rodbolt]

Re: Yamaha OX66 Mystery Alarm

HJohnson.
post a new topic.
post your engines full model number.
post what the tach visuals indicate.
this hread is over 3 years old.
post it and we will look at it.
wish Raynuedecker still posted.