New boat, new member, engine rough idle

[Mattr82]

Hi guys, new member here, looking for some advice. Long time boater, first time jet boat owner as of a couple of months ago. I have already learned a ton about my boat, in the short time that I have been on this site. Thanks for all the wisdom that is shared!

2013 242 Hour meter says motors have about 62 hours on them. Motors both fire up and run, but initially run rough and have a concerning about of vibration. I have taken the boat out 3 times now, and each time the extra noise and vibration s when engine is above idle at any kind of speed.

Initially I though the sound may be impeller against the housing, so I removed the impeller, one of the impeller housings was swollen and the impeller rubbed against it. I thought this maybe was my problem so I ordered the parts. Although that was a problem, it has not solved the problem, I fired the motor up again, still makes the noise/vibration.

Tried posting a video. Tells me the upload file does not have a valid extension. Anyone know what to tell the new guy?

 

[Weeb]

I think you have to post the video to YouTube first then you can import it. I’m not tech savvy so there might be another way also.

 

[Mattr82]

Link to my video posted. See if this works.

slightly longer clip.

 

[Mattr82]

@Weeb thanks for the advice!

 

[mark_m]

Hmm. You may want to change the oil and spark plugs. I wonder if you do not have all of the plug coils connected?

 

[Skysurfer2010]

Has it been in the water since winterized? It could just be fogging oil that needs to be burned off. Run the engines on a hose for 15 mins and see if they smooth out.

 

[Mattr82]

@Skysurfer2010 have had it out three times this year. Ran for 45 minutes the last time I had it out. Has not seemed to change much.

 

[Skysurfer2010]

@Skysurfer2010 have had it out three times this year. Ran for 45 minutes the last time I had it out. Has not seemed to change much.

Probably could use new plugs then.

 

[PJ73]

Is it both engines of just one? Run down the list, Plugs, EFI, fuel filter... I don't hear any knocking or valve tap. Almost sounds like a misfire.

 

[Gym]

Anytime you buy a "preowned" boat you want to go through it. Change oil, oil filters & spark plugs. Check air filters and lubricate boat and trailer parts.

I agree with previous posts regarding spark plugs and coil wires. You also may have a bad coil. While changing your spark plugs you can swap your coils from the starboard engine to the port to see if your problem moves. I'm sure your issue can be resolved pretty easily.

 

[Mattr82]

@PJ73 Both engines run rough, although the starboard side may be slightly worse. Since it is both engines, I don't think swapping the coils from one engine to the other will tell me anything.

I just replaced the plugs on the starboard engine, it didn't make a difference in the sound. I suppose I will try the coils next, anyone point me towards a certain place to buy them, brand to buy etc?

@Gym I do hope this can be resolved pretty easily, It is easy for me to let myself go down the what-if path... and worry about all the major things that could be much more costly.

If it is a coil, will I do any damage to anything else if I run it prior to replacing it? Cause, man it will be tough to let it sit this weekend if it is nice out...

 

[Mattr82]

Yikes, just looked at pricing for new coils. Guess I'm not just buying 4 of them to see if that helps. Is there a way to test them? If the coil is bad, will I not have spark in a plug, or just not consistently have spark in a plug?

 

[Troy JK]

I would change the plugs and run a heavy dose of seafoam. I have seen seafoam clean out dirty injectors.
also I would try running it on the hose for a cpl minutes and use a spray bottle to squirt water onto the exhaust manifold, towards the top where the ports separate from each other. if You squirt them all and only one cylinder doesnt sizzle, you’ll know that one cylinder isn’t running, probably due to a bad coil.

 

[Gym]

@PJ73 Both engines run rough, although the starboard side may be slightly worse. Since it is both engines, I don't think swapping the coils from one engine to the other will tell me anything.

I just replaced the plugs on the starboard engine, it didn't make a difference in the sound. I suppose I will try the coils next, anyone point me towards a certain place to buy them, brand to buy etc?

@Gym I do hope this can be resolved pretty easily, It is easy for me to let myself go down the what-if path... and worry about all the major things that could be much more costly.

If it is a coil, will I do any damage to anything else if I run it prior to replacing it? Cause, man it will be tough to let it sit this weekend if it is nice out...

Not to rain on your parade @Mattr82 but anytime you run an engine not running correctly you can risk uneven wear or possible damage. Engines are meant to run "in balance". When they don't you put additional wear on internal parts like cam & crankshaft. The vibration pretty much says it all.

When you changed the plugs did you put in the plugs recommended by the manufacturer or did you just replace what was in there? Did you check the plug gap? Did you notice if there was any burn Mark's on the coil boot indicating a high tension leak.

You make a good point about both engines being affected. Is your fuel old or possibly contaminated with water? I know I'm throwing a lot out but this would be my mental checklist of things to check.

 

[Gym]

Yikes, just looked at pricing for new coils. Guess I'm not just buying 4 of them to see if that helps. Is there a way to test them? If the coil is bad, will I not have spark in a plug, or just not consistently have spark in a plug?

Check for burn Mark's on the side of the coil boot. Make sure your 12 volt primary leads are plugged securely into the top of the coil and they are not damaged. They should click on securely.

 

[Mattr82]

@gythanks for the responses.

Update on the rough idle and steps taken to correct.

Replaced the plugs on port side engine. I did check plug gap prior to installation. Yes, replaced with factory spec plugs. No discernable markings on the plugs themselves or coil boots.

Fired engine up, same as before. Then, to attempt to see if any of the coils were bad, I unplugged each coil while running for a second or two. I wanted to find if there was a coil that, when unplugged, did not make a difference in sound of the engine, therefore meaning that coil wasnt operating properly.

Both engines, one by one on the coils, affected the idle (made worse), so I assumed it wasnt the coils at fault.

The sound when I unplugged each coil, was similar to the sound of the rough idle, just worse.

In my mind at this point was that it may actually just need a good cleaning of injectors and fuel treatment as some suggested earlier in this thread. Or at least I hoped that was what it was, so, off to the store to get some seafoam. I gave it a heavy dose of seafoam, and saturday on the water I ran the engines pretty good. After a few minutes the engines sounded, well, listen for yourself.

I suppose this means I will run seafoam from now until, well, forever.

 

[fireflymedic]

I use sea foam at beginning of every season and try to run that first tank of fuel to empty to get rid of any bad gas. They say 1 apple spoils the whole bunch well one gallon of bad gas does the same thing in these small engines. Imho

 

[FLJetBoater]

I'm getting that same sound as you

I haven't replaced the plugs yet (will do this week) but I did run 23 gallons of gas through it after adding 48oz of seafoam to the full 50gal tank. But given that you replaced the plugs and it didn't change anything, I'm not confident that's the cause. How much seafoam did you add to your tank? Maybe the 1oz/gal I added wasn't enough to make a difference.

 

[sunbyrned]

That’s how mine have always sounded and my plugs, gas, oil have always been maintained well. The boat has always run like a charm. What should they sound like?

 

[FLJetBoater]

That’s how mine have always sounded and my plugs, gas, oil have always been maintained well. The boat has always run like a charm. What should they sound like?

Listen to the video from post #16 in this thread. Sounds MUCH cleaner.