Yamaha OX66 experts help I have a gremlin

[slavis]

Re: Yamaha OX66 experts help I have a gremlin

Also in the service manual it says "power unit seal" could be a cause for poor acceleration. Could this be a factor?

 

[PBJohn]

Re: Yamaha OX66 experts help I have a gremlin

How do the spark plugs look? Any fouled or lean burn.

 

[slavis]

Re: Yamaha OX66 experts help I have a gremlin

Plugs look normal just like the other side. I even installed new plugs problem persisted and then swapped plugs problem persisted. I have swapped everything (I can think of). Unless it is internal I am at a total loss. Anybody know of a good 2000 or newer 250 OX66?

 

[PBJohn]

Re: Yamaha OX66 experts help I have a gremlin

Compression and leakdown test will tell you if you have an internal issue. Reading the plugs can also give you an indication as to what cylinders are affected. My guess is you have some type of electrical issue. Did you try swapping the main engine relay? Check the 10 pin connector at the engine? Key on engine off try wiggling and pulling on the harnesses and listen for clicking relays, pump, inj, ect.

 

[slavis]

Re: Yamaha OX66 experts help I have a gremlin

What is the main engine relay? I did swap all the electrical side cdi,wire harness,coils,plug wires,stator, etc.. Also hooked up a short 10 pin cord directly to the motor side to bypass the igniton switch,kill switch, and ignition cord. No effect.

 

[PBJohn]

Re: Yamaha OX66 experts help I have a gremlin

Inside the electrical box (black box) There's a black relay I believe it has red/yel wires and some others. If you trace from the O2 sensor this is the power feed to the O2.

 

[jwbergeron]

Re: Yamaha OX66 experts help I have a gremlin

That relay is a bugger....took me a hole season to find out that was the cause of my motor cutting out randomly (like someone turned the key off). It controls power to the fuel system. Not sure if it would cause only a drop in RPM's...that sounds more like the bad O2 sensor I had.

 

[slavis]

Re: Yamaha OX66 experts help I have a gremlin

Pretty sure I already swapped that but I will double check. Thanks for the tip. Please keep the ideas coming

 

[jwbergeron]

Re: Yamaha OX66 experts help I have a gremlin

You said you swapped the vst tank...did you swap the entire vst assembly (i.e. the high pressure fuel pump inside also)? I've had similar issues...seems like it was always either the vst or 02 sensor. I did have a problem with a fuel line at a bend just upstream of my fuel filters...it had worn away against the hull and was occasionally sucking air.

 

[slavis]

Re: Yamaha OX66 experts help I have a gremlin

Yes I did swap the entire vst tank including rhe rails/hoses/injectors/lp pumps/ fuel canister etc. etc. ....

 

[rodbolt]

Re: Yamaha OX66 experts help I have a gremlin

have you ever tested stator outputs when the problem is occuring? have you ever tested CDI output or secondary Kv while its occuring?
secondary Kv or CDI output will rapidly confirm or eliminate ign.
with code 1 displayed while it is dying all the sensor inputs to the ECU make the ECU happy.
your making this way to complicated for such a simple EFI system.
do these mechanics have fuel and electrical certifications from yamaha on the shop wall?
a master tech cert would be even better.

 

[slavis]

Re: Yamaha OX66 experts help I have a gremlin

DING DING DING I think we have a winner. Wanted to look at the upper crank shaft seal thnking maybe it was a vacuum leak ( I was really reaching). Took the flywheel off took the stator off and noticed "another" ring with a harmess. It is called the charge coil. When I swapped the stator I never noticed it I was so focused on the stator. Took it off and noticed corrosion on the tabs. Cleaned it up swapped it with the other side. Ran the boat 10 miles and NEVER surged. Come to find out the winky blinky will only pick this up if it has a short. The function is to tell the computer when to fire the plugs. This makes sense because I had fuel I had spark and I had timing. I also wanted to mention a couple of points I noticed about the 250 ox66 that other owners might want to check. The fuel hose coming from the bottom of the fuel rail sits against a vacuum hose connected to the silencer box. On both of my motors the fuel hose was worn 1/2 way thru from vibration. Also the wire from the stator that goes into the electrical box (it has 3 green wires or 2 green and 1 black) has a quick disconnect. Of all the connections I went through this one was the only one with corrosion (was the same on both motors). Others might want to check/change this hose and check/add dielectric grease to that one connection. Thanks for all the help. If on my next trip I am wrong about my solution I will post the info. Thanks Rodbolt for the last post. Yes my yammi mech can do all that but I could not get him here until thursday. He usuall is booked 2-3 weeks out (he is the best I know of)

 

[99yam40]

Re: Yamaha OX66 experts help I have a gremlin

I am not really that knowledgeable on those motors but you have covered most of what is on the motors except for the spark and timing

An inductive timing light will help you see if you have spark problems on certain cylinders and also tell you if the timing is staying steady while problem occurs. A high voltage tester would be better for testing ignition coil outputs but not too many have them.
A peak reading voltmeter made for measuring these ignition systems or a DVA adapter and DVM or DMM will show the pulsar coil and charge coil outputs along with the outputs of the CDI to the coils. Taken while problem is occurring may show something if you are dropping spark to one or more cylinders.

Just my 2 cents

Good to see you have found your problem.

I did get close with my post on testing inputs and outputs to CDI. I believe a DVA would have showed something as problem was occurring.

 

[rodbolt]

Re: Yamaha OX66 experts help I have a gremlin

ding ding
had you folloed my first posts about testing CDI output or secondary Kv you would have nailed this some weeks ago.
the winky blinky will only show a code when it is ACTIVE.
if the ecu sees all its pulser coil inputs it sets no codes and the blinky shows code 1.
had you run it at the problem RPM when the problem was active you would have seen code 13.
glad ya found it, even happier ya did it before you trashed a powerhead.
just another note, the OX66 motors also use the pulser coil signals to trigger the injectors.
the injectors inject the fuel AND the lubricating oil.
see why splatter gunning can be bad?

 

[slavis]

Re: Yamaha OX66 experts help I have a gremlin

My hats off to 99yam40 and rodbolt you guys sound like you know your stuff. Wish I understood what you mean by testing cdi output or secondary kv. I will go through the service manual and try to learn more. I know there are test harnesses I might have to purchase to do some of these other tests. When I had a problem with the tps I purchased that harness. Rodbolt I did run the winky blinky while the motor was surging (I had this in one of my prior posts) and no error code showed up. Are you saying it should have showed up at that time? Or should the cdi output test or secondary kv test showed the problem. The charge coil was not bad it only had corrosion on the contacts.

 

[slavis]

Re: Yamaha OX66 experts help I have a gremlin

Also what is "splatter gunning"?

 

[99yam40]

Re: Yamaha OX66 experts help I have a gremlin

Just throwing parts at it without having some test tell you what the problem is or at least rule out things that are not the problem. Testing by the book is the best way, without skipping a step.
And when you change a part then start all over with the testing. It usually only take a few minutes to retest once you have the tools and equipment and the knowledge.

 

[99yam40]

Re: Yamaha OX66 experts help I have a gremlin

I am not sure how fast the codes will be throw out, but a code should be put out if there is not the proper outputs from the coils, which a bad connection would/could cause.
In general the charge coils charge the capacitors in the CDI and the pulsar coils tell it when to fire, but things are different on some motors that I am not familiar with.
Still learning, but can not remember everything if you do not use it every day

 

[rodbolt]

Re: Yamaha OX66 experts help I have a gremlin

splatter gunning is just that.
its doing a lot of stuff and accomplishing nothing.
usually caused by lack of a troubleshooting plan and a lack of understanding what the machine does and what your test equipment is telling you.
CDI output is a voltage output from the CDI unit to the ign coil primaries and on an outboard like yours is measured with a PEAK reading type meter. NOT an RMS meter.
I own 5, 2 digital and 3 stevens CD77.
Kv testing is testing the ign coil output,secondary, voltage usually in the 7 to 10 Kv(Kilo Volt) range.
if secondary or primary voltages are stable at the surge range you know the ign producing components are working, if timing is also stable you know that ign controlling circuits are working.
on the Ox66 the pulser coils not only control the CDI output it also controls fuel injector firing time.
lose a pulser input and code 13 is displayed and that ign coil doesnt fire and the injector it controls doesnt provide fuel.
takes 5 minutes to test the CDI output on all 6 cylinders.
the drawback to the CD77,or any analog meter, is they are polarity sensitive, the advantage is they can quickly show intermittant voltage loss or spikes.
I have posted extensivly on how the OX66 system works on both the 2.6L and the 3.1L both with and without the CCS system.

 

[slavis]

Re: Yamaha OX66 experts help I have a gremlin

Thanks for the explanations. I went through the service manual again and understand slightly better what you are talking about. Also made a list of the equip amd harnesses needed to conduct the tests you are talking about. Please clarify-Should the winky blinky have picked up a poor "contact" from the charge coil (I did it at idle/during surging)? Best I could tell the injectors were still getting fuel and firing and the plugs were still sparking but I think at the wrong time.