1999 Yamaha 225 smokey at idle and rough at low RPM

[retooferab]

Please pardon if this has been answered. I've been reading and reading and haven't found an answer.

Motor: 1999 Yamaha 225 V-Max ox66, (oil and fuel injected)

Boat: 1988 Ski Centurion Warrior Barefoot Comp (20 ft, 1100 lbs w/o motor)

Symptoms:
Smokes excessively at idle and just off-idle.
Runs rough/stumbles until about 2200 RPM.
Idle sometimes rumbles down to 4-500 RPM.

NO problems starting, or running at higher RPM's/speeds.

Problem:
Makes speed maintenance a real pain for little skiers in the 12-20MPH range. Also difficult to teach technical starts like backwards deepwater barefoot.

Tried:
Paid local Yamaha tech $400ish to replace the oxygen sensor and "solve the problem" which may have involved other tests... but no substantive work. It now runs as bad as ever; no improvement at all.

After looking at a friend's Yamaha manual, I was unable to pinpoint the problem. After studying the Clymer manual, tried to test for Vapor Separator Tank flooding which listed the exact symptoms I'm having. It mentioned the motor would stumble because it's given excess fuel (through flooding VST) and then burn it efficiently at higher RPM's... The test was to disconnect the vent hose on top of VST, squeeze the primer bulb, and see if any fuel exited the vent hose fitting. Since the diagram was slightly untrue to my motor, I had to guess at the fitting... but I tried two with no hint at all of fuel seeping out.

Now what?? I love my boat, my motor and my money... don't want to flush more away at dealer for no improvement. (They did NOT water test it and have no means to do so near their shop.)

What other information is needed for this diagnosis/solution?

Thank you so much in advance!

 

[yamamarinetech40]

Re: 1999 Yamaha 225 smokey at idle and rough at low RPM

ok, you said you paid the local Yamaha tech(does that mean dealer or side) to replace the 02 sensor...do you mean you requested that or he found it defective? I don't know the history of your motor but I would reccomend a good decarbing with Power Tune or equiv. and THEN clean the o2 sensor and change the plugs...before to run the crap out of it before changing and cleaning after decarb.....you would be amazed at how much carbon can build up if ringfree not run regularly....

 

[retooferab]

Re: 1999 Yamaha 225 smokey at idle and rough at low RPM

ok, you said you paid the local Yamaha tech(does that mean dealer or side) to replace the 02 sensor...do you mean you requested that or he found it defective? I don't know the history of your motor but I would reccomend a good decarbing with Power Tune or equiv. and THEN clean the o2 sensor and change the plugs...before to run the crap out of it before changing and cleaning after decarb.....you would be amazed at how much carbon can build up if ringfree not run regularly....

Thanks for the reply

I simply asked Yamaha (dealer) Service to "fix it" given the symptoms I presented above. Not sure how much testing was done, but he said there was a service bulletin on the O2 sensor and replaced it... ASSuming, perhaps, that was the cause of my symptoms? Nothing else was done, to my knowledge, that addressed the problem. And it didn't run better, even for a while, after this service.

History of motor by previous owner's report:
Bought in 1999, used once each summer for a week. Mostly it sat... claiming <100 hours on the motor (no meter).

So, based on it smoking at idle and not running well at low RPM's...
1. Decarb with Power Tune or equivalent.
2. Clean O2 sensor (with what??).
3. Change plugs.

OK... I'll give that a try and report back. Please feel free to share other recommendations in the meantime.

 

[rodbolt]

Re: 1999 Yamaha 225 smokey at idle and rough at low RPM

test the spark plug caps for proper resistance, test the coolant temp sensor for proper output.
the O2 sensor can be tested with a 22 dollar or homemade adapter and the three tech bullitens that are avalible using a DVM. its the only way to insure its operating correctly.
attach a fuel pressure test guage to the high pressure rail. turn the key on and pressure should come to about 35 PSI and stay above 25 PSI when the pump shuts off. if it does not look for a leaking regulator or leaking injectors.
also an oil output test should be run, I usually do it as a comsumption test as occasionally the oil pump shaft seals will leak and the engine will draw extra oil past the pump shaft.
you may have the dealer install a diagnostic test lamp to check for any sensor codes set, the O2 sensor has no code.
its also rather pricy which is why I test them both before and after cleaning/replacing.
the Vmax engines DO NOT use the CCS system that the other 3.1L motors use.
dont get lost with it .
how I do the consumption test is to unplug the oil feed line from the lower part of the engine oil tank,insert a syringe and fill it. then you can run the engine at the specified RPM and the specified link arm setting and see exactly what the engine is consuming.
a good link and sync may help as well.

 

[retooferab]

Re: 1999 Yamaha 225 smokey at idle and rough at low RPM

Thank you, rodbolt! I've read enough here to fully respect your advice.
Unfortunately, I'll have to do some reading and study to comprehend your suggestions. I'll try what I can and report back.
I suppose if all else fails I can take what I learn here to a Yamaha service expert... I mean, I don't mind paying a reasonable fee IF the problem is solved!

Thanks again, and I'll let y'all know progress. (Probably won't get to boat till later this week.)

 

[retooferab]

Re: 1999 Yamaha 225 smokey at idle and rough at low RPM

UPDATE: Problem solved... returned... getting solved again?

What solved the problem was cleaning Oxygen Sensor and all the stuff around it, including plunger thingie. Though dealer (reportedly) replaced the sensor, it was only after we cleaned all the black gunk outta the plunger area, off the plunger, off the sensor (etc) that it ran as intended.

Of course, we got so happy about how well Sea Foam cleaned the parts that we soaked the cylinders and sprayed Deep Creep in the intake... y'know, to enjoy the smoke show. Then, surprise! It started to run like crap again at low RPM's. We're pretty sure we just re-introduced blank gunky stuff into the O2 sensor and surrounding parts when we sea-foamed it... and my son has it apart right now to re-clean it all. Hope this works and stays good for a while.

Any idea what causes the re-occuring problem (other than two morons de-carbing it all after cleaning)? Oh, btw, the spark plugs looked different than ever before after our cleaning and Sea Foam bath... more dry and brown than oily.

I'll report back. In the meantime, I appreciate additional comments and suggestions.

Peace

OK, just talked to my son and he said there was some gunky stuff in there but not nearly as much as before. He said the plunger was sticky and he got it "un-sticky" so we'll see in an hour how it runs. Any incite to the plunger and how to make sure it's happy in there?

TIA!

 

[rodbolt]

Re: 1999 Yamaha 225 smokey at idle and rough at low RPM

no insight
the ONLY way to insure the O2 sensor is working properly is with the 3 tech bullitens and a DVM. anything else is a poke-N-hope.
poke-N-hope can get expensive and usually wont fix a yamaha.
the 3.1L motors usually need about 5 threads cut off the link arm to properly set the oil arm adjustment.
most techs cant or wont properly set the thing.
dunno why, but most keep hitting the high tech stuff and forget about the low tech.
have the fuel pumps and VST ever been serviced ?
if you look at the maint schedule its broken into hours OR a calander period.

 

[retooferab]

Re: 1999 Yamaha 225 smokey at idle and rough at low RPM

More good news/bad news...

Ran great after the cleaning... for an hour or so, then gradually returned to the crappy performance of old. The motor is such a joy when it's running right, which makes this problem even more maddening.

Our local guru (that's you Ed!) led us to the solutions so far. And he said with this year (1999) ox66 there's a screen/mesh thingie that likewise gets all clogged up and needs cleaning/clearing. Apparently later models do not have this, but it only changes with a new power head! Also advised me that we'd have to clean everything out a couple more times before it was all clean and happy and stayed that way longer.

Also, he mentioned that rodbolt might recommend not only poking through the mesh... but (gasp) even removing it! I'm waiting to follow my son into the motor since Ed showed him. But again, help and advice is appreciated.

Rodbolt, does the oil arm adjustment make sense in light of this pattern (rough/clean/smooth/rough/clean/smooth/rough....)? Heck, I'm more than happy to find a solution, no matter how high or low tech. Thank you so much for your help. Again, we'll tackle it and report back.

Err.. slight problem now with testing since river is closed from flooding... Guess we'll tinker and clean, and test 'er out when the waters subside. Meanwhile, building a bigger ark.

I don't have any evidence of fuel pump or vst service. I know I checked the vst for possible flooding early on, and found no problem (not that I knew what I was doing). I used to think the motor ran decent at higher RPMS and therefore concluded there wasn't a fuel pump issue. Now it seems to me that since it runs great after cleaning it isn't the fuel pumps?? VST, though? Maybe?

 

[TonyNoriega]

Re: 1999 Yamaha 225 smokey at idle and rough at low RPM

RODBOLT here's a related but different question for you: I'm a new owner of a 200hpdi (it's a 2001 model), and I am not a mechanic - just a user......but I like to have a comprehensive understanding of how my motor works.

I have a CD version of the Yamaha service manual --- do you think I would benefit from buying a Clymer manual? Is it different enough, or 'layman friendly' enough that it would be useful?

Thank you!!!!

 

[rodbolt]

Re: 1999 Yamaha 225 smokey at idle and rough at low RPM

cant think of a mesh thingie.
never saw it. the replacement 3.1L blocks had a running change in the O2 sensor holder and block. make sure the correct parts are being installed as the mounting gaskets changed in mid 03, so if the block has been replaced since mid 03 and your using the 99 gaskets it wont work correctly.
there is a tech bulliten out on it .
the VST has a filter at the high pressure pump inlet and one behind the fuel pressure regulator.
both need periodic maint to insure correct fuel pressure is maintained.
but the only way to check the O2 sensor is with a DVM.

the rest you just have to check and eliminate as a cause for a rough running or rich running condition.
fuel rail presure,oil pump adjustments and ign system testing, once proper compresion has been verified.