1998 Yamaha 225 OX66

[Captain Ken]

A continuation from a previous post, lost RPM's at WOT on motor, max was about 3500. Went through entire fuel system and had technician look at it and put diagnostic light on, which intially showed code 33 (knock sensor?) but that eventually cleared and all was normal. After running motor for the guy he tells me it appears to be a bad fuel situation, most likely water in fuel.

Thus far I have replaced all 3 LP fuel pumps, swapped the O2 sensor with the other motor, cleaned the VST filter and replaced all filters. Upon pulling the plugs it appeared the lower two cylinders on the stbd side of the motor had more carbon build up than the others.
I'm also seeing some gas residual in the water, coming from the exhaust I assume while idling the motor.

I switched fuel supply from port motor to stbd and vice versa, checked fuel system vacuum as well as rail pressure on problem motor, all appears OK and according to spec.

Last time I tested the motor the situation seemed to worsen with the motor not sounding right and cutting out at about 2500-3000 rpm on occasion and a vibration being felt in the throttle control as the motor died. Eventually I got the motor running again but was only able to obtain 3500-3800 rpm.

At this point I'm fairly convinced its an electronic or firing issue of some sort.

Any advice on how to further troubleshoot?

 

[JUSTINTIME]

Re: 1998 Yamaha 225 OX66

test coil input volts
u have a high and low speed stator
the high speed stator kicks in around 2500

 

[bigbrownbuku]

Re: 1998 Yamaha 225 OX66

start with the basics. change the plugs. setup your tps. and check the plug cap resistances. these are usaually in the 5-8k range? then go for anothe test run on a different fuel tank.

 

[rodbolt]

Re: 1998 Yamaha 225 OX66

ok
3 fuel pumps means it a 3.1L motor
V76
the charge coils on a V76 feed port and stbd bank there is no high and low speed.
I dont wish to bust justintimes chops but as a tech most the info he has posted is at best iffy.

justintime, if you wish to converse I will. your good but you fail to extract the info needed.
keep posting.

captainken
find a real tech
find one NOW
code 33 is normal for a cold engine, it signifies the motor is in warm up mode and will shift to code 1 after warm up is complete. been that way since about 1990 on the V76 engines.
captain ken
do you have the service manual and the O2 sesnor test harness as well as a DVM?

 

[Suncoug]

Re: 1998 Yamaha 225 OX66

Captain Ken,

Out of curiosity, have you checked the fuel pressure while running the motor? Also, if you have Yamaha fuel management, how is the fuel consumption? Any difference on the problem motor vs. the other?

Looking at my Yam service manual, (33), as rodbolt said, indicates "ingition timing is being slightly correctly (when starting a cold engine)". It would need to read code (17) for it to be "Incorrect knocking sensor input signal".

Also does rpm fluctuate during idle only or at all rpm range?

 

[Captain Ken]

Re: 1998 Yamaha 225 OX66

Suncoug - Yes as previously stated I did check fuel pressure while running, maintained a constant 35 PSI. Fuel consumption on the problem motor does appear higher as well, and as I said I'm seeing signs of unburnt fuel in the water while at idle in neutral.

Rodbolt - Yes I have the manual, learned quite a bit since having the difficulty. I cleaned the O2 sensor on the problem motor as well as the other motror. I then swapped the O2 sensors between motors with no difference after doing so.

I'm bringing the boat in tomorrow morning to a local Yamaha tech, hopefully he's of good quality and can help me out. There is no other diagnostic equipment that can be hooked up to this motor other than the light I'm hearing? Sounds like the year 2000 and newer have computer hook up capabilities?

I'll explain everything I've done to this point but it sounds to me like some sort of sensor or ignition/firing issue at this point. I dont have the capability to set up the TPS or check voltage on various sensors etc so I think it best I bring it in to someone in the know.

Thanks for the input, I'm on an accelerated learning curve here and I will keep you posted.

 

[rodbolt]

Re: 1998 Yamaha 225 OX66

some tests you will want your tech to run, spark and compression.
if they pass start the engine with the diagnostic lamp installed.
if it sets code 33 then reverts to code one its not a sensor.
if anyother code is set but code 1 go find the problem.
if the thermosensor fails two things happen, one is idle speed is increased and two is code 33 wont reset to code 1.
depending on if its an s225 or vmax 225 the the engine will run on 5 or 4 cylinders at various RPMs below 2000 and above 500.
its imperative to test the O2 sensor output after cleaning its the only way to tell if they actually work.
this can only be accomplised with a DVM,the test harness and the gearcase submerged.
the only failsafe for the O2 sensor is if the ECU sees it as unplugged, then fuel injection is fixed rich.
the ign system is fairly straight fwd yamaha with the exception of the high and low speed charge coils are actually port and stbd bank coils. even though some tune up guides list them as high and low.
yes there are misprints.
its quick and easy to run a few tests.
one is pulser coil output,then charge coil output then CDI output, the above tests must be done with the correct test harness and a peak reading type meter or DVM with compatable adapter.
the above test is where the tech has to understand the CCS system used with EFI V76 motors or he gets bit.
while the system looks complex its really not if you break it down into subsystems and follow a logical path.
thats why I do spark and compression first and simultaneously.
if I get good spark on all six at cranking speeds and the compression is good I wasted 7 min and confirmed the engine mechanically is sound and the ign system is capeable of generating spark.
then to further eliminate ign I test pulser outputs,charge coil outputs and CDI outputs,remembering its a CCS system or not depending on model prefix.
once I have eliminated engine mechanical and engine ign systems I start looking at fuel and fuel controls.
like I say this stuff aint difficult and sometimes I am embarresed to charge what I do but it requires knowledge of all the systems and how the react to each other.
if you suspect dirty fuel remember there is a filter under the fuel pressure regulator and 10 micron filters in the actual injectors.
the injectors on that engine are easy to access and have a look at.

 

[Captain Ken]

Re: 1998 Yamaha 225 OX66

Thanks Rodbolt, in reading previous posts I see that you have a comprehensive understanding of what you do. I dropped the boat off this morning and spoke to the shop today and asked if he wanted me to forward some info from someone who I felt was in the know. He told me he would have his technician check it out and get back to me if he needed more help/info.....lets hope that means he's confident in his tech.

As for the injectors, I comprehended cleaning and checking them but based on what I saw with the very clean VST tank and filter and what the motor was doing I dont see that as the culprit here. I was told to get a pulsator and clean the injectors with carb cleaner and blow out with air, is that the reccomended cleaning method on the injectors?

 

[rodbolt]

Re: 1998 Yamaha 225 OX66

if I suspect them its all of 5 min to remove them for inspection. there is a 10 micron filter on the injector inlet.
if they are clean I spray them ,oil the orings and reinstall them. if they are dirty I send them to Flagship Marine in FL for cleaning and flow testing. I am sure there are a lot of places that clean them however flagship has always done a good job and so far will turn them in 24 hours.
and yes not all techs are incompetent, however those that are tend to make it hard for those that are not.
as far as my competence all I can say is I have seen one or two and did stay at a holiday inn once.
but dont offer outside information to a tech unless you suspect they are incompetent. then the only assisitance they need is on how to properly hook up the trailer.
good luck.

 

[Captain Ken]

Re: 1998 Yamaha 225 OX66

Spoke to tech this afternoon, said he replaced the O2 sensor, set up the TPS, changed the plugs and ran the motor, ran fine and at WOT achieved 4900 RPM. Also said motor seems to run a bit rough at idle speeds which has been the case since I bought the boat a month ago. Said he'd have to dig further into it to figure out that problem.
Told him I cleaned the O2 sensor and swapped it with the one on the other motor to no avail last week, as well as changed the plugs less than a month ago. He asked me if I cleaned the tube going into the exhaust housing which I didn't.
I guess it goes to your point about the only real way to test the sensor was to put a meter on it, which I couldn't do.

Going to meet him tomorrow morning to review his work and run the boat myself but it sounds like the problem may be resolved.....$1000 later. As I had swapped the O2 sensors myself I guess I'm wondering if the sensor itself was bad or simply the cleaning the port going into the exhaust resolved the issue.

I'll fill you in after I speak to him tomorrow.

 

[Captain Ken]

Re: 1998 Yamaha 225 OX66

Picked the boat up yesterday, all seems to be fine, topped out at 4900 RPM. Technician also found exhaust plate leak on other motor which I'm embarrased I never saw. Running the motors without the covers on once in a while is a good idea I would guess huh?

I guess after understanding the issue, the rattling back and forth I heard on the O2 sensor dumbell thingy should have flagged the issue in the first place. I may have misunderstood and written otherwise in my previous post but I was unaware that there was supposed to be a hole in the center of the dumbell. But again, you need to find the right person to troubleshoot these issues. In speaking with the tech that serviced the boat I'm confident in his abilities and I would feel good and confident in bringing further issues to him in the future.

Thanks for your insight.

 

[rodbolt]

Re: 1998 Yamaha 225 OX66

on the 3.1L motors prior to the 03 midyear block change when the O2 sensor draw tube clogs it will tap and sound just like a loose wristpin.
book says to clean the tube,sensor and holder every 200 hours or annually whichever comes first.
running output voltage from the O2 sensor should fluctuate between about .3 and .6 V.
it should not stay steady and should not be lower or higher.