vx225 vibration and smoke

Hello All

I've got a 2002 Yamaha VX225 Ox66 3.1 EFI motor(VX225TLRA). It has a vibration in it around 2300-2500rpm, can be felt in neutral or in gear and is not prop or lower unit related. (tried other props, checked prop shaft and it is spot on).

It smokes a lot at idle, especially when starting after sitting or cold, but is generally very smokey. I think fuel consumption is high - 2 gallons per hour at idle in neutral at 730rpm for example.

At steady 3000rpm, the o2 sensor reads between 200mv and 400mv, generally around 250-330mv. At idle it generally stays above 650mv, but fluctuates between 550mv and 900mv. Generally around 800mv.

I cleaned the old sensor but the results did not change. A new sensor still gave the same results.

Have also cleaned the VST needle, checked 3 low pressure fuel pump diapraghms, sync and link, oil linkage adjustment and checked plug caps (all same, about 5k or whatever the service manual said).

Motor currently idles at 730 when warm and 850-900 when cold. I know it should be 1200 when cold - what should I check for this?

I read a lot here before posting!

My questions:

* is my o2 sensor reading OK at 730rpm idle? If not, what could cause this?
* is there any cylinder shutdown between 2000rpm and 3000rpm on these motors.
* Any suggestions re warmup idle being only 850-900rpm and not 1100?

Rodbolt says here http://forums.iboats.com/bbBoard.cgi?a=viewthread;fid=30;gtid=969224;gpid=969235 that a VX225 "will cut cylinders 2 and 4 when the shift switch is activated from idle to 3000 RPM". Does this mean that some cylinders are shutdown when in gear at up to 3000rpm? If so, can this be bypassed so that all 6 run all the time?

Any suggestions on what to do next would be apprecaited.

Thank you

Re: vx225 vibration and smoke

if in fact a VX motor it does not use the CCS it only incorperates a shift cut switch.
you will need to check for proper fuel pressure on the high pressure rail and check the CDI output with a DVA meter.
you may also wish to test the TPS 5 V reference as well as TPS output at the suspect RPM range. its also possible to have a faulty crank position sensor,air temp sensor or air pressure sensor.
with the diagnostic lamp if any sensor has actually failed it will show as a code.
when you cleaned the O2 sensor did you remove the housing and draw tube for cleaning as well ?
your numbers look awful rich at low speeds.

Re: vx225 vibration and smoke

Thank you for your reply Rodbolt.

I will work through the list, hopefully this week and come back with an update.

Your reply leads me to some more questions:

The powerhead has been replaced. How can I tell if it is a VX or a normal Ox66 powerhead? I assume it is just the computer that is different between the two? Is there a part number or tell tale?

Is a DVA meter a digital volt meter?

I had removed the housing and draw tube and cleaned them as well as the sensor. They were actually pretty good to begin with except for some powedered carbon around the draw tube.

I don't have access to the winky blinky. Is there a way that I can make one or monitor certain pins with a multimeter? It will be about two weeks before I can get one due to freight.

I thought my low speed numbers were rich also. I don't really see what could cause that.

Thank you for your feedback, I will work through your list and report back as soon as I have got through it.

Re: vx225 vibration and smoke

the DVA adapter works with a number of digital voltmeters but no a DVA of itself is not a meter.
some top end DMM's have a DVA setting not to be confused with an RMS function.
seirra tools sells an analog meter that has a DVA function thats a merc equivalent tool.
if you can make the proper adapters then most all the sensors are testable with a DMM. I did see a knock sensor that was unplugged once that gave similar symptoms,however the idle should be a bit faster and ign timing will be fixed.
most the sensors on that motor use a 5 volt reference and either a thermistor or pick of voltage for feedback to the ECU. lose the 5 volts and the ECU may see the feed back as a failed sensor.
thats why we test them before replacing them.

Re: vx225 vibration and smoke

Rodbolt,

I took the boat out the other day and started it in glass calm water. There was a lot of unburned fuel on top of the water and it made a lot of smoke.

I assume this means that heaps of extra fuel is getting past the injectors some how.

As I understand it there are only three ways this can happen:

1. Injector stuck on (unlikely?)
2. VST needle stuck (happens?)
3. low pressure lift pumps leaking through diapragm (most common?)

Since it is an easy task and I don't yet have all the tools to perform the tests you recommended, I thought I would check the lift pumps again.

The dealer rebuilt/checked them for me about two weeks ago, but he only had one kit. He thought the diapragms looked fine and they didn't seem to leak or have a hole if he stretched them.

I put them back on myself afterwards so he didn't have the opportunity to test them properly.

Anyway, I unbolted the top and bottom ones and both were leaking fuel badly. I didn't loosen the screws, just undid the two bolts that hold the pumps to the block. The middle one is harder to get at so I didn't check it, but I guess it is time to replace all three anyway.

Would this explain why at idle it is running rich but at running revs it isn't? Would this also make it run rough at middle revs?

Does the fuel that is leaking past the diapragms run into all six cylinders?

Thank you for your help so far.

Re: vx225 vibration and smoke

I replaced the fuel pumps yesterday which seemed to fix the smoke issue. Much, much better, although it did smoke once after restarting. It seems to be smoother although not perfect.

I will need to make the necessary adaptors etc to perform the tests Rodbolt has suggested.

At idle I'm still getting 02 readings of mostly around 800mv with some fluction above and below that. The o2 reading comes right at 3000rpm. It is still up towards 800mv at 2900rpm and everything below that. At 3000 it seems to come down to about 300mv.

If the ignition timing was fixed, how many horsepower would I lose? I bought the motor second hand and have never seen it run properly. I suspect it is quite a bit down on power. I'd like to check the timing with a light to see if it is fixed and not advancing properly.

The TPS reference is just over 5 volts (5.08 I think it was) and the TPS itself is set to 5.2 with the throttle arm unclipped (shutter fully closed). A sync and lync has been completed.

I will go through the service manual to find the details I need. I will test that each sensor you have mentioned is getting 5v and hopefully I can also work out a method to get winky blinky results but reading from my dmm. Can't be that hard!

Thank you for your help so far.

Re: vx225 vibration and smoke

Correction, the TPS, with the throttle arm disconnection is 0.52 volts.

Re: vx225 vibration and smoke

go back to the basics and eliminate the obvious.

check for spark, if you have no spark on a cylinder you will not burn the fuel and have a very rich condition for the o2 sensor and you will see fuel on the surface.

Re: vx225 vibration and smoke

Hi All

An update.

I reset the TPS to 0.504 volts and the o2 sensor tested around 200mv at idle after warmup. I only plugged my meter into the back of the plug (not the proper test harness) so I'll recheck it later, but that seems to probably have fixed the rich condition at low revs.

The fuel pumps seem to have almost fixed the smoke issue.

I have found the motor is missing the exhaust gasket from the lower unit, this would be allowing exhaust back up into the cowling (instead of underwater and out the exhaust ports) making the cold smoke look worse.

The vibration is a lot better, I think it was the sync and link that resolved that. Being a big block motor, I assume I should not expect it to be quite as smooth as a 2.6.

I have also found the motor was missing a couple of parts from where the waterpump connets to the water tube feeding into the powerhead. I don't know exactly how these are supposed to go on.

The missing parts are 1, 3 (both for waterpump to water tube) and 7 (exhaust gasket) in the link below. How the exhaust gasket fits is pretty obvious. How the two water seals go on, I'm not really sure. They will just slide on but they don't seal like that.

http://www.boats.net/yamaha/partsys...rd&year=2002&model=VX225TLRA&component=334476

Thank you for your help so far.

Re: vx225 vibration and smoke

1 and 3 basically slide on the tube when the case is installed. They should be installed in the pump housing first with the rubber teat going onto the hole in the housing. Normally leaving them out will reduce the water pressure substancialy.

Re: vx225 vibration and smoke

Thanks Ray

I'm still a bit confused. On this page 22 and 23 go inside the water pump. http://www.boats.net/yamaha/partsys...rd&year=2002&model=VX225TLRA&component=334611

22 there is the same part number as 3 on the other page.

But 23 and 2 are different. Also, looking closely at the first link I showed, I thought the picture looked like the water pump was complete (including 22 and 23) and that 2 and 3 were also required to go on somewhere.

At the moment, I have 22 and 23 in my water pump but water is still escaping, I think from there.

I hope I have explained my confusion properly.

Thanks again for the help

Re: vx225 vibration and smoke

Ray

I've found 22 and 23, they are further up the tube. They are both called seals, but one of them appears to be more of a vibration dampner.

Anyway, they are in place.

I'll do some more testing and come back with the results

Thank you everybody for your help

Re: vx225 vibration and smoke

An update: replacing the plastic water seal at the top of the water pump has stopped the water leak. It was slightly sloppy and had a couple of grooves.

Problems remaining are:

* Vibration (feel it through the whole boat) around 2300-2600rpm
* Occasionally really smokey at startup, sometimes a dream for a normal two stroke
* Surging when changing throttle settings around 2200-2600rpm. Once the speed settles it holds
* Warms up at 900rpm starts to reduce from there almost immediately (doesn't sit at 900rpm for more than 20 seconds) and runs at 730rpm but should warm up at 1200rpm

Other things of note, using a timing gun I have verified that all 6 cylinders are firing at all revs least until 3000rpm (didn't bother above that). Timing is advancing, cylinder one starts at about -4 and advances to +20 by 4500rpm or less. I didn't think to check timing at the problem rpm.


I have the o2 sensor test harness and the tps harness. I don't have access to any other specific test gear and so have not yet been able to perform the tests that rodbolt has suggested. I would really like to be able to make a winky blinky or something that would allow me to use a multimeter to read these costs. Anybody have any experience with this.

It would be a shame to purchase a winky blinky and still not be any the wiser to the problem, but I know this is about my next step.

Could the vibration be retarding the timing at the problem RPMs? Would this cause the problems I am having with the surging?

Also, does anybody know what could be wrong to make it not warm up at 1200rpm?

Thank you

Re: vx225 vibration and smoke

failure to warm up will either be defective t-stats or a defectivce thermosensor, all are testable.
the ECU relies on the thermosensor for engine temp data, if one or both are bad you get garbage in-garbage out.on you motor all the inputs to the ECU and most of the outputs can be monitored with a DVM and the correct or even incorrect break out boxs(test harnesses)
I am crazy busy and also in the process of moving my household but I will try to copy and fwd a few pages from the school book on CCS and VX 76 as wellas OX66 systems as they re;late to a 3.1.
per chance, have you tested the resistance of all the spark plug caps ?

Re: vx225 vibration and smoke

Thanks Rodbolt

I have checked the plug caps, all are within spec (about 5K from memory).

There is an unused wire on the harness that connects to the oil tank inside the motor. I assume this is the wire the winky blinky uses - could this be correct? Can I just parallel onto this wire somehow, connect the other wire of my DMM to ground and watch the voltage on a DMM instead of using a winky?

Re: vx225 vibration and smoke

Thank you Rodbolt, Ray and others for your help

I've worked out what was wrong. I had a large electrical load which comes on with the key switch (via relay). I charged the battery, disabled the load and now it is perfect. Doesn't surge. Much, much, much snappier performance and the smoke now minimal except on cold start.

I can't remember the voltage it was running, was over 12 but it is now over 14. I suspect it was the o2 heater element not getting enough voltage to heat as much as necessary.

Thank you again for your help.

Re: vx225 vibration and smoke

Listen to Rodbolt(much smarter than I),but I have found a low battery, bad battery or bad connections to the battery cause these issues also! Mikel