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  1. #1

    2014 Yamha FXHO Rough Idle issue

    Hello all.
    I've got a 2014 FXHO and it has developed a rough idle, and wondering if anyone has some insight to what the issue might be

    About the ski:
    175 Hours
    95% of use is in saltwater
    I use it for ocean fishing and trolling for salmon, so at least 30-40 of those hours are at idle/slow speed.
    Ski is flushed and cleaned after every use. I finish off the flush with Salt Away
    Regular oil changes.
    I run normal pump fuel that has ethanol.
    New spark plugs last summer at '100 hour service' at the dealer.
    Has run perfectly until this recent issue.

    The issue:
    Had a great day of fishing on the ocean and right at the end of the day (after a 30+min drift with engine off) I started it up to go in and it began to have some problems. It would run for a second then shut off. Took about 5 tries to get it running and only stayed running after giving it some throttle. Then it was rough on the idle, almost as if the engine was missing. Drove it around a bit and it seemed to be ok, and then crossed over the bar and took it to the ramp. My guess it was a fuel delivery issue or a spark issue.
    Back at home I cleaned and flushed it but it was running fine on the hose. No issues.
    Thought maybe the problem was solved but figured it was a good time as any to run some injector cleaner through it. I picked up some quality fuel system cleaner (BG Products. Good stuff!) and added to my half full tank. Took the ski to the river to burn through the fuel and at it dock it started idling rough again. Again, after some throttle and keeping the RPM's above idle it seemed to run ok. Took it for a 20-30mi run and burned through most of the gas. Got back to the dock and the problem seemed to be gone.
    I thought about replacing the spark plugs but my local shop was out of stock. (ordered them online, should be here in a few days) Instead I double checked them and they all looked clean and in good condition. The gaps we're a little off, 1 to 1.1mm, so I re-gaped them all to 0.8mm.
    Started it up in the driveway on the hose and was great. No issues.
    This last weekend I took it out on the water and the issue was back.....straight away at the boat ramp it was idling rough. I drove it around a bit and it seemed to get a little better. Then I'd sit for a while with it off. Start it back up and it would be rough again.
    I then hopped in the water next to the ski so I could listen to the engine better and had my girlfriend start it. It seemed like there was some rattling noise or a bearing type noise coming from it. Noise was more from the back towards the intake/impeller area, if that makes sense. Was hard to pinpoint. Then when she would rev the engine, the noise would go away. As the rpm's dropped the noise and roughness came back.
    So, it seems the issue only comes from when the ski is in the water and under load. It also only seems to be there when the engine is cold, as it seems to idle fine after it's been running awhile.

    Any ideas on what it could be?
    Thanks!


  2. #2
    I say spark plugs. I change mine once a year regardless of hours or after 50 hrs because I don’t want a fouled plug

  3. #3
    Thor's Avatar
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    Quote Originally Posted by seabrook View Post
    I say spark plugs. I change mine once a year regardless of hours or after 50 hrs because I don’t want a fouled plug
    A big + 1 on that (we do ours every 40 hours cuz, well, relatively speaking, plugs are cheap AND, at least in our VXR, the difference when we drop new plugs in it is noticeable to everyone riding it! (not sure why that is with this 4-stroke and not other (i.e., car engines) but, maybe it has something to do with fact our ski stays on the water, parked on a floating port, 24/7 from May - Oct … dunno ...)

    Chester, fingers crossed those new plugs solve the issue; what your're doing with your machine sounds positively awesome and inspiring!

  4. #4

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    This post reminded me to order new plugs.......

    could be a coil failing producing weak spark at low rpms but usually it’s when hot and high rpm coil issues appear.....

    noise could be jet pump bearings they dont last for ever......or mid shaft bearings have they been greased?

  5. #5
    TimeBandit's Avatar
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    Chester123,
    As I was first reading your post, it sounded a lot like that one-off / long(hard to)-start phenomenon that these engines have on rare occasions out of the blue. Basically, after a typical shutdown, the subsequent restart of the already warmed engine just keeps turning over and over but not starting. Repeated attempts and finally the motor comes back to life, yet very rough as if it were previously flooded.
    However.... as I continued your post, I see you are still having issues, so it must not be the notorious long-start. Or, it is/was a long-start, and now the subsequent fuel treatment is affecting your AFRs right now.
    Noises at idle - you are likely too hyper-aware right now. Probably something else, if not nothing.
    New plugs? Yeah, get that done with a fresh clean tank of fuel before you go any further, as the rough idle is common when one cyl drops out. Could be going in and out with temp differences.
    Another issue (given the age) a possible air-leak due to a failed gasket/union where the throttle-body attaches (yet this is more common in SC engines).
    If none of the above, time to move toward ignition coils and FI testing.

  6. #6
    Thanks for the ideas! Much appreciated.

    New plugs showed up today. Gapped and installed them and took it to the boat ramp. Problem solved! Still didn't seem to be the smoothest idle its ever had but maybe I'm being over critical/hyper aware...
    Idled great and no odd noises. So I think this one is solved.

    Quote Originally Posted by HDAV View Post

    noise could be jet pump bearings they dont last for ever......or mid shaft bearings have they been greased?
    Not sure if the dealer greased them when I took it in last summer but I've never greased them. New item added to the maintenance list!

  7. #7
    Quote Originally Posted by TimeBandit View Post
    Chester123,
    As I was first reading your post, it sounded a lot like that one-off / long(hard to)-start phenomenon that these engines have on rare occasions out of the blue. Basically, after a typical shutdown, the subsequent restart of the already warmed engine just keeps turning over and over but not starting.
    This has definitely happened to me! Always randomly and out of the blue. I was never sure if it was just my machine or happened to others. good to know it's a known issue.
    Thanks!

  8. #8
    Aaaaaaaand I spoke too soon..... :/
    took it out fishing yesterday and it was working fine at the ramp and worked great for about half the day. Then, of course when we’re several miles down the coast, it started doing the same rough idle issue. Trouble starting it and then was idling rough. It would stay rough until about 3k-4K rpm and then would work past it and run smoothly at higher rpms. After running it a bit it would idle ok, and would run at speed fine. Made a straight run back to the dock and worked fine. After pulling the trailer down I started it to put on the trailer and it was rough again.
    So, I’m guessing it’s coil or injector issues. With my limited experience on these machines, my guess would be the coil. It seems once the engine is spinning fast enough to get good current from the stator it gives the weak coil enough juice to make a worthwhile spark.
    Ill start with testing the coils I guess. Anyone have a good tip on how to test them? (Other than grabbing onto it and seeing if you get shocked ��)

  9. #9

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    I have a service manual I will look up the coils spec and test procedure and try and let you know mine is an older SHO but coils may be the same

  10. #10
    TimeBandit's Avatar
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    Quote Originally Posted by Chester123 View Post
    ....
    So, I’m guessing it’s coil or injector issues.
    ....
    Could be. But it also could be a bad signal wire (bad connector) to either of these.

    As far a troubleshooting the coils ... these skis have electronic ignition systems, so the spark strength won't change with stator health or rpm differences. Besides, there are no high-voltage wires ... as the coils are built into the spark plug boots.
    The way to "test" coils is to ohm them on a bench first and check the values measured with the service manual. You ohm the spark side to ground, then all three pins. If you don't have the manual, ohm all the coils and compare among them - all should get the same general values.
    The next way is an Active Test using YDS. You pull the plug, attach it to a spark plug tester tool, reconnect the coil, then using a live YDS session initiate the ignition test. YDS will command the ECU to then pulse the desired plug for 5 seconds, enough for you to observe the sparks in the tester.

    Don't forget about a possible air leak where throttle-body (TBV) attaches to front the intake manifold. Reach down, grab a hold of the TBV and see if you can get any separation in union plate. You could also try this while idling in the driveway, to see if the idle changes good/bad.

    Another possibility ... temperature sensor (or the connector plug). Remember, these are computer-controlled fueling/timing, so in correct temp and or pressure data could have the ECU flipping to the wrong fuel maps - although that should pop a code. YDS can help here as well, by showing real-time temp data from the sensor.

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