2001 150 ox66 Alarm when key on, limp mode

[99yam40]

if it fails, O2 feed back is not used. there will be NO group injection. ign timing is fixed at 7*btdc,idle speed increases and top speed cannot be reached.

any sensor that assists in ign timing,CPS,TPS battery voltage,yellow wire at the ECU unplugged,ECT will cause base timing to go to 7*BTDC and idle speed to about 1100.
the ECT will set base timing at 7*BTDC idle speed increases yet timing will advance.

NOTICE I keep coming back to ign timing at 7*BTDC and increased idle??????

I believe he is asking if the ect. will also cause group injection.
I believe it will, but I am not positive if all Rod posted as ect.will, or just some of it

[rodbolt17]

get this stupid anganeer stuff out of the brain pan.
the engineering work was done 20 years ago.

the ONLY time group injection is done is rapid acceleration or deacceleration.

UNLESS something freaking BROKE, then ign timing is raised to 7*BTDC and IDLE speed increases.
this is to let the operator know something is WRONG.

other than that its synchroneous injection.

yes Virginia its that stupidly simple.

the only engineering work is to understand a stupidly simple speed density EFI set up that's been about since the 80's on various engines.

[Yamaholic]

its a simple two wire coil.
a small A/C voltage altenator.
any two wire coil should have both legs checked for shorts to ground.
there is a peak voltage test for loaded and unloaded.just wondering what the loaded and unloaded differences are if this voltage is directly proportional to rpm? or is it not?

if it fails, O2 feed back is not used. there will be NO group injection. ign timing is fixed at 7*btdc,idle speed increases and top speed cannot be reached.If it fails, o2 feedback is not used? you are saying that if the cps fails, no o2 feed back is used? or do you mean the o2 sensor?

any sensor that assists in ign timing,CPS,TPS battery voltage,yellow wire at the ECU unplugged,ECT will cause base timing to go to 7*BTDC and idle speed to about 1100.with the ECU yellow wire unplugged, I can't reach the same rpm and speed as I do with the CPS unplugged. it will still try to accelerate but the rpms will get cut back the same as when the CPS is plugged in.
the ECT will set base timing at 7*BTDC idle speed increases yet timing will advance.timing will advance, fuel is not fixed, so my only problem is a somewhat rather poor idle? also had a look at the teeth on the flywheel and couldn't find either tooth that was different. what should I be looking for?

NOTICE I keep coming back to ign timing at 7*BTDC and increased idle?????? yes, I do but why? no one is disagreeing with you.
guessing that you have owned this engine or own and engine like this. any issues that you can remember that were similar? are you still thinking that it is fuel? why does unplugging the cps let the engine have more fuel? as always, any answers are appreciated.

[99yam40]

Apparently I was completely wrong about the injection among other things.
thought Rod said something about it being different or fixed like the timing, so thought it did something different.
Sorry/

And I have no manual for your motor , do you yet?

have you tested timing or fuel pressure yet, or anything?

Is the idle high?
Is the timing at 7 instead of where it should be?

[rodbolt17]

dude
what kinda engineer are you?

there are TWO basic ways to produce an A/C voltage, not getting into solid state.

1 is spin a coil around a magnetic field.
2 is spin a magnetic field past a coil.

yes Virginia its that simple.

now to produce MORE voltage there are THREE ways.
1 increase the strength of the field.
2 increase the number of turns of wire in the coil.
3 simply spin it faster.

basic 7th grade physical science.

if the CPS fails O2 sensor feed back is ignored.

if the O2 sensor fails,other than OPEN or SHORTED the stupid ECU simply doesn't know and will trim fuel for whatever feedback it gets.

if UNPLUGGED the ECU will fix fuel rich at low speed and lean above 4000 RPM.
yes I have owned a few however I am a Yamaha master tech and have worked with OX66 since the late ninties.
unless your using an ocilliscope,which I doubt, your looking for nothing on the flywheel.


ninty nine percent of the OX66 issues are fuel related.

ALL sensors are testable with a standard digital meter with a peak reading adapter or a peak reading meter.
RMS is NOT peak.

ANY out of range sensor that assists in ign timing control,other than O2, will set BASE ign timing at 7* BTDC and idle speed WILL increase.
learn this simple truth.

O2 sensor voltage has NO alarms or ECU actions unless its unplugged or shorted.

unplugging the CPS will NOT increase fuel. it will disallow GROUP injection that's used for rapid acceleration and deceleration.

rail pressure and clean injectors are CRITICAL.
to much or to little rail pressure and the engine runs like crap.
clogged injector or dirty nipple can make it run crappy.

first thing to look at is spark,rail pressure,compression and ign timing.
typically at warm idle you will see about 2-3* ATDC.
somefolks will try to use the shutter stop screw to fix the idle issue.
notice I said shutter stop screw and NOT idle speed screw????????

[Yamaholic]

dude
what kinda engineer are you?

there are TWO basic ways to produce an A/C voltage, not getting into solid state.

1 is spin a coil around a magnetic field.
2 is spin a magnetic field past a coil.

yes Virginia its that simple.

now to produce MORE voltage there are THREE ways.
1 increase the strength of the field.
2 increase the number of turns of wire in the coil.
3 simply spin it faster.

basic 7th grade physical science.
why the hell are you explaining how this shit works? we all know how this works. just answer the questions that I am asking. What is the difference in the loaded and unloaded testing of the CPS? the way I see it is RPMs are RPMs, loaded or not. Correct? if not I am sure you would love to tell me how I am wrong. Maybe if you could get past the point of me being an anganeer, you might be able to focus all of you knowledge on the questions that I am asking.

if the CPS fails O2 sensor feed back is ignored. thanks

if the O2 sensor fails,other than OPEN or SHORTED the stupid ECU simply doesn't know and will trim fuel for whatever feedback it gets.

if UNPLUGGEDyou mean the O2 sensor? the ECU will fix fuel rich at low speed and lean above 4000 RPM.
yes I have owned a few however I am a Yamaha master tech and have worked with OX66 since the late ninties.what shop do you work at? maybe if I am close I will drop by and have a chat with you.
unless your using an ocilliscope,which I doubt, your looking for nothing on the flywheel. ok perfect


ninty nine percent of the OX66 issues are fuel related.again, can you explain why I get plenty of fuel with the CPS unplugged but it goes into rpm reduction when plugged in? or fuel starvation as you think it is? if the pump isn't supplying enough pressure with the cps plugged in, why will it supply enough when it is unplugged? that doesn't make sense in my mind.

ALL sensors are testable with a standard digital meter with a peak reading adapter or a peak reading meter.
RMS is NOT peak.

ANY out of range sensor that assists in ign timing control,other than O2, will set BASE ign timing at 7* BTDC and idle speed WILL increase.
learn this simple truth.

O2 sensor voltage has NO alarms or ECU actions unless its unplugged or shorted.

unplugging the CPS will NOT increase fuel. it will disallow GROUP injection that's used for rapid acceleration and deceleration.thanks

rail pressure and clean injectors are CRITICAL. They are all brand new, including pump
to much or to little rail pressure and the engine runs like crap.
clogged injector or dirty nipple can make it run crappy.they are all clean as I stated on page 2

first thing to look at is spark,rail pressure,compression and ign timing.spark is good, compression is 115. rail pressure and timing I will check(although, engine is smooth at idle and up through, doesn't smoke, vibrate. if timing is off, would it cause the engine to go into the rpm reduction?
typically at warm idle you will see about 2-3* ATDC.
somefolks will try to use the shutter stop screw to fix the idle issue.
notice I said shutter stop screw and NOT idle speed screw????????

[Yamaholic]

Apparently I was completely wrong about the injection among other things.
thought Rod said something about it being different or fixed like the timing, so thought it did something different.
Sorrythanks anyway

And I have no manual for your motor , do you yet? not yet

have you tested timing or fuel pressure yet, or anything?neither yet

Is the idle high?idle is higher when I unplug cps. it still runs on 4 at idle with unplugged but will run on 6 when I hit the throttle and will run fine(or pretty close) at wot. not sure if I can use the Mercury rpm gauge that is on my boat. guessing they all just run on charging voltage?? maybe this would help in the troubleshooting
Is the timing at 7 instead of where it should be?haven't checked yet.

[rodbolt17]

unloaded simply means the device is unplugged, yes voltage will be slightly higher.
what your looking for is does the CPS generate a signal of the correct voltage UNLOADED then rerun the test LOADED. isolates what is causing any CPS issues.

this engine does NOT use CCS.
this engine sparks and injects all cylinders at all RPM's.
not a lot of operational theory in the manual.

tach signal is genetrated by the ECU based on pulser coil input.

a quick run out at the failure RPM and load with a diagnostic test lamp attached will save a lot of easter egging and ghost hunting.
at the same time it would be a good time to test rail pressure.

[Yamaholic]

unloaded simply means the device is unplugged, yes voltage will be slightly higher.
what your looking for is does the CPS generate a signal of the correct voltage UNLOADED then rerun the test LOADED. isolates what is causing any CPS issues.
thanks for the info

this engine does NOT use CCS.
this engine sparks and injects all cylinders at all RPM's.
not a lot of operational theory in the manual.agree

tach signal is genetrated by the ECU based on pulser coil input.agree

a quick run out at the failure RPM and load with a diagnostic test lamp attached will save a lot of easter egging and ghost hunting.
at the same time it would be a good time to test rail pressure.thanks for the info this time. I will test the rail pressure when I get time and a tester.

I am still looking for a reason why the fuel pump will feed the engines needs when the cps is unplugged but goes into limp mode with it plugged in? there is no alarm either.
my alarm stays on after I start the engine for about 40 seconds, then goes off. not sure what is up with the alarm.

[boscoe99]

If the motor had gone to a Yamaha mechanic when this thread first started you would have long since been out on the water and enjoying boating.

It is not too late to have a mechanic inspect and correct whatever the problem may be.

[boscoe99]

unloaded simply means the device is unplugged, yes voltage will be slightly higher.
what your looking for is does the CPS generate a signal of the correct voltage UNLOADED then rerun the test LOADED. isolates what is causing any CPS issues.

this engine does NOT use CCS.
this engine sparks and injects all cylinders at all RPM's.
not a lot of operational theory in the manual.

tach signal is genetrated by the ECU based on pulser coil input.

a quick run out at the failure RPM and load with a diagnostic test lamp attached will save a lot of easter egging and ghost hunting.
at the same time it would be a good time to test rail pressure.

Boy is that an understatement.

You must be part British.

[Yamaholic]

I would rather spend many hours trouble shooting this engine and understanding how it works and not even use it than bring to a Yamaha mechanic. the Yamaha mechanic is no good to me when I am 30 miles offshore. If there is one thing that I did learn from my years as a shrimp/crab fisherman, is that you need to know how to fix your own equipment. If you don't understand how things work, you will never understand how to fix them. I have until next spring to trouble shoot this engine. Im in no rush. if you guys are in a rush, just don't bother to read this thread.

by the way, I purchased this engine from a guy who had it at the dealer to get it running. I picked up the engine from the YAMAHA dealer and was told it was running perfect. I have since gone back to the mechanic and asked him about the issues and he insists that the engine was fine. It does run fine on a stand which is the extent of most mechanics knowledge that I have dealt with. They must be like anganeers I guess! lol I have found that the experts are the people who use the engines and do their own work, not just on a stand in a shop. Don't think that just because YAMAHA engines are known to be bulletproof that the mechanics are great as well. It doesn't work that way.
That is why we have forums like this.

[99yam40]

Apparently I was completely wrong about the injection among other things.
thought Rod said something about it being different or fixed like the timing, so thought it did something different.
Sorrythanks anyway

And I have no manual for your motor , do you yet? not yet

have you tested timing or fuel pressure yet, or anything?neither yet

Is the idle high?idle is higher when I unplug cps. it still runs on 4 at idle with unplugged but will run on 6 when I hit the throttle and will run fine(or pretty close) at wot. not sure if I can use the Mercury rpm gauge that is on my boat. guessing they all just run on charging voltage?? maybe this would help in the troubleshooting
Is the timing at 7 instead of where it should be?haven't checked yet.

Does not sound like you have done much troubleshooting if you have not tested anything yet.

If it is not sparking all 6 at idle you can chase ignition.
if it is sparking all 6 then you chase fuel.

Compression, spark,timing ,and fuel. the 1st 3 are easy to test, but fuel pressure is also

[Yamaholic]

99YAm40,
I haven't done a great deal of troubleshooting yet as my time is very limited. I do however like to challenge the suggestions that people give for validity and if nothing else to learn how things work. I don't mind being wrong as long as I learn from it.
I understood that this engine doesn't fire on all 6 at idle??? I think 2 and 5 cut out below a certain rpm. correct me if I am wrong.
anyway, I do appreciate the help that people give. thanks for your suggestions.

[99yam40]

Rodbolt is a Yamaha master tech and shares his knowledge on this site, just because he wants to help
Pay attention to what he posts
I am fairly sure He has told you several times in this thread that that motor is suppose to spark all cylinders all of the time. You may need to go back and reread the whole thing again