Starboard Engine Shakes (OX66 Yamaha SS)

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grady33

GreatGrady Captain
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Location
Ocean Pines, MD
Model
Express 330
Noticed that the starboard engine is shaking and causing vibration at idle speed up 800-1000 RPMs. Had the dealer check over engine, adjust linkage, test spark plug wires etc. Everything was fine which is leading me to believe the problem may be Fuel Injectors. Has anyone run into this before and can anyone think of something I may be missing? How much does it cost to get the injectors serviced?

Once the boat reaches above trolling speed, it rums great. Today we burned roughly 18 GPH at 3500 rpms cruising at 28 knots. Filters, VST, spark plugs, o2 sensor all cleans in June. Dealer tested the O2 sensor and it was working fine.
 
Cleaning is about $125 if you remove them. It is easy to do.
 
grady28 said:
Noticed that the starboard engine is shaking and causing vibration at idle speed up 800-1000 RPMs. Had the dealer check over engine, adjust linkage, test spark plug wires etc. Everything was fine which is leading me to believe the problem may be Fuel Injectors. Has anyone run into this before and can anyone think of something I may be missing? How much does it cost to get the injectors serviced?

Once the boat reaches above trolling speed, it rums great. Today we burned roughly 18 GPH at 3500 rpms cruising at 28 knots. Filters, VST, spark plugs, o2 sensor all cleans in June. Dealer tested the O2 sensor and it was working fine.
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If it shakes at idle and the idle seems a bit low, I would look at low pressure fuel pumps. If you had bad injectors, i would expect issues across the rpm ranges
 
I thought about the Low Pressure pumps but changed them about 3 years ago. Last time I had a problem with one, it caused me to drop RPMs but didn't shake. I may go ahead and change them out. Boat is for sale and potential buyer is concerned. Had the boat checked out and compression and linkage and spark plug adaptors and filters etc were all fine or replaced.

Great boat posted on the for sale section. Dropped price form $46,500 to $41,000. Will consider any reasonable offers. Pictures available @ http://s1271.photobucket.com/albums/jj6 ... dStevens1/ . Send me a PM or email me at fshnoc@yahoo.com.

Family Affair - Any suggestions on where to send out the fuel injectors? Looking for quick turn around.

Thanks,
David
 
I think I used "fuel injector man" out of Naples. Fast and professional.
 
I have had the "shaking" engine 2x on my port motor, but I have 4-strokes..both times it was an injector, but I still have a rough running engine..it just was not as noticible at cruising speeds...last season the mechanic replaced 1 and it went away..this year they did all 4...problem went away but I dont know which ones were causing the issue..and I dont know that the mechanic knows either..I think I may have gotten schtupped but they did fix the problem...
 
At the advise of my dealer, I did a shock treatment today using ring free. Mixed 3 gal with 7-8 oz of ring free and connected directly to the engine filter. Ran about 2.5 gal thru revving engine, and shutting down for 20 mins and then running again. After finishing, replaced with new spark plugs and engine seems to run better. Took for a ride and ran WOT at 5200 RPMs. Engines are YAM 225 OX66 2 strokes. After running it a bit came back and engine was much better but still shaked a little but no where near as much as before. It was smoking a little bit more than port engine leading me to believe it may be running a little rich on the oil. Does anyone know how to adjust the oil? Should I try anything else?
 
I wouldn't touch the oil if you have had no issues previously.
I have the same engine. Mine misses at low rpm occasionally and I can't find a permanent solution. My engine either has 'gremlin ' that comes and goes, or these engines are simply fickle.
A bad low pressure pump can cause the engine to run rich (smoke) and miss at low rpm. Keep us informed on your success.
 
grady28 said:
At the advise of my dealer, I did a shock treatment today using ring free. Mixed 3 gal with 7-8 oz of ring free and connected directly to the engine filter. Ran about 2.5 gal thru revving engine, and shutting down for 20 mins and then running again. After finishing, replaced with new spark plugs and engine seems to run better. Took for a ride and ran WOT at 5200 RPMs. Engines are YAM 225 OX66 2 strokes. After running it a bit came back and engine was much better but still shaked a little but no where near as much as before. It was smoking a little bit more than port engine leading me to believe it may be running a little rich on the oil. Does anyone know how to adjust the oil? Should I try anything else?
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If you can determine the color of the excessive smoke, that would help with a fix. Blacker smoke is causedby a too rich fuel mixture. Bluish smoke comes from excessive oil. White smoke is a bad sign and is caused by water in the combustion chamber or exhaust system.
The oil adjustment is called oil pump synchronization and is relatively simple to check but you really need the manual to help you identify the parts to look at. Basically,there is a linkage from the throttle to the oil pump. That linkage moves as the throttle is moved and the oil pump arm should be just about touching the stop when the throttle is closed. The oil pump arm is spring loaded and if the linkage is disconnected or broken, the spring makes the moves the arm towards max oil flow. Now, if the motor is running at WOT or near to it, the oil pump will normally be at max flow position so if you have smoking at WOT, it is probably NOT the oil pump adjustment.

Note that the fact that the shock treatment helped is a good sign but after that treatment you have to go over all the routine checks again. The treatment can loosen and move gunk around. Plugs are most likely to get fouled as is the O2 thimble or O2 sensor.
I am curious about one thing. Did you routinely use Ring Free or was the shock treatment the first time?
 
Thanks for the reply. I have always used ring free at every fill up and occasionally add more - usually once a year. There really isn't too much smoke but one does smoke a tiny bit more than the other. I took some video and will try and post it somewhere once I edit it.
 
GTOMAN said:
I had an OX66, 225 HP that did not run well at idle and replacing the thermostat fixed it.
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I am not sure I get the connection. Did it run rough after the typical warm up period or when it was a cold start.
Are you sure it was the thermostat and not the thermo switch?
 
It ran rough at idle all the time. Occasionally it would cut off while I was slow trolling. I am pretty sure it was the thermostats, but with my memory these days, I cannot swear to it. You may want to question a service man before you spend the money. I think I was told by my service man, who is not one to needlessly add parts, that they needed to be replaced every 2-3 years due to salt causing them to stick up.
 
We replaced the thermostats in June so I doubt this could be the cause. What is the other Thermo sensor? A tiny bit rougher at idle up to 700 rpms. Anything over up to WOT, it runs great!
 
grady28 said:
We replaced the thermostats in June so I doubt this could be the cause. What is the other Thermo sensor? A tiny bit rougher at idle up to 700 rpms. Anything over up to WOT, it runs great!
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That motor should idle at about 730. Below 650 or so, it will shake and possible stall. A low idle could be caused by something as simple as an idle adjustment or could be a symptom of other issues.

There is one thermo switch and two thermo sensors. The thermo sensors tell the control unit what the water temp is and the computer uses that along with other sensor data to adjust fuel/ air ratio and timing.
 
Thought I'd post an update. WELL after lots of checking this and checking that, it turned out to be a bad 02 SENSOR. It was checked and tested within limits but after 12 years, apparently (according to Yamaha) they have run their life and probably should be replaced. Now both engines are running perfectly and smooth. That's a good thing cause the boat is for sale. Having purchased a 330 Express, there is no way I can afford to have 2 Grady's - although the thought did cross my mind. Thanks to everyone's suggestions.
 
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