2007 155 GTI SE Vibration Issue - Please help

[fizzman911]

Hey everyone, this is my first time posting here. I recently purchased a 2007 155 GTI SE with 100hrs on it. It was very well taken care of, adult owned and garage kept. I was hoping maybe some of you can help me diagnose an issue I am having.

After taking the Ski out for a couple of times over a week period I noticed my ski started to vibrate or shake. I noticed that the engine started to sound a bit different/rough and there would be a lot of vibration. This started randomly after idling for about 15 min. I turned the motor off and then on again to see if that would solve the issue. It did not. The vibration/shaking started off very light and it got worse over the course of 2-3 min. When I would bleep the throttle or keep RPMs higher I noticed that it would smooth out. The first time it happened I gave it some gas and rode around for about 5 min and a couple of times I gave it WOT to see if maybe it needed to clean itself out. After this the Ski had no more issues for the rest of the day. This was towards the end of the day riding though.

The next time I used the ski was 6 weeks later, last weekend. I took it out and initially had no issues for the first 2 hours. Then I noticed I started to get a slight vibration again roughness. This got worse for another 2 minutes and then stayed the same. I could tell it was not running very well. So again I gave it gas and rode it around, sometimes hard, for about 3 min and the ski got better for about 30 min. Unfortunately it continued to act up and after giving it gas it would only stop the shaking/vibrating for a couple of minutes.

I feel that when I get it off idle the vibration gets a lot better, the engine smooth's out. When the RPMs drop it starts to act shake and vibrate. I did feel that there might have been a slight lack in power at lower RPMs when it was shaking then when it was not. I don't want to do any damage to the motor so I will stop using it until I figure out what is causing the issue.

To start I will replace all plugs, look at the motor mount points to check for damage. I have a lot of knowledge working with cars and motorcycles but not with Jet Skis. I appreciate any advice.

 

[fizzman911]

Someone also told me remove the pump housing and check for something that I might have sucked up in there.

 

[IDoSeaDoo]

There are two common causes of vibration. Cavitation, and Engine vibration. Sucking up sticks or debris into the pump can cause severe cavitation, which manifests itself as vibrations. Usually, I will know when to expect this, as I'll see stuff floating around. The best thing to do after you suck something up is to shut off the engine. Chances are, it'll float out on its own. If not, pulling the craft out of the water will usually dislodge it and it'll flow out on its own. If it makes it past the impeller, it can get stuck on the pump vanes. Usually, these instances result in you losing the ability to go fast, or even get on plane, but will let you limp home at idle speed. I had a small 5" long reed, half the diameter of a pencil get stuck there, and the boat would not go past 30mph, and vibrate like crazy at higher rpm/speed. I couldn't believe that such a tiny, flimsy thing could change the pump dynamics so much and survive those conditions long enough to be discovered upon disassembly. I've also had a rock do the same thing on another boat. You can try to remove the nozzle and see if you can spot anything through the vanes.
Re-reading your post, it sounds like your vibrations are in the lower RPM and go away when you give it gas? This points to an engine issue. I assume you're not getting any check engine lights or warnings from the gauge cluster? These types of vibration could be the result of a bad plug, or coil. Definitely change the plugs and re-test, but also carefully inspect each coil. They sometimes go bad and can be felt at lower RPM. Unfortunately, I'm not sure of the accepted methods of testing these aside from measuring the resistance and maybe attaching a spark-tester to one and cranking the motor over. If you hold the throttle wide open as you crank, the engine goes into a diagnostic mode and cranks without giving fuel. You can test compression and other things by doing so. Maybe someone else can chime in on how to diagnose the coils.

 

[Milehighguy303]

I have have the same 2007 GTI SE 155 ski and love it. Hope you will too when you get this figured out. Definitely rule out your jet pump with a visual inspection, and then start with plugs and most of the time that will solve issues with this durable ski. I only use the NGK recommended plugs and get them locally - my auto store stocks them and they are $3 or less each. I don’t know how to diagnose coils without equipment, but that is probably the next step if plugs don’t solve it. For whatever it is worth, I have 200 hours on my ski and original coils. These machines like good plugs and I replace mine every year, just because $9 is cheap insurance for a great running machine. I also occasionally a couple times a year dump a can of B-12 carburetor cleaner in a full tank before I go ride to keep my fuel injectors clean. I have not replaced my fuel injectors either. I use 89 octane gas. Good luck - you bought a great ski!

 

[fizzman911]

Thanks for your reply’s everyone. I took the ski out to a local river and used it for a couple of hours with no issues. Before that I did replace the plugs and then found sheared fuel pump wires. I figured that was the issue and fixed them.

Unfortunatly this weekend I took it to the beach and had similar issues. I feel this happens when I idle for a bit longer than normal. When it starts I kinds of feel like something is off. It then get worse over the course of a couple of minutes. Once I give it a bit of throttle it goes away but after a while it still vibrates even when giving it more gas. I think it smooths out at higher rpms. I ended up turning it off and anchoring it while at the beach. I came back to it and there was no more vibration. Throughout the day I felt I ran well after that. I don’t think I am sucking anything in. I also removed the pump housing and there was nothing there. This afternoon I looked at the engine mounts and the bolts are all right and motor mounts look good. Dont know how easy it would be to spot if one was broken. The problem is that this normally happens after idling for a while so I don’t know how to test the ski for the issue since I can’t leave it running out of water. I will try running some injector cleaner. I am also using premium ethanol free gas. I will try checking the coils too.

The ski runs very well when it does not have this issue.

Any other advice I appreciate it.

Thx

 

[Milehighguy303]

I think you have adequately eliminated a mechanical issue with the jet pump - which is good news. And spark plugs are now good, so you are probably down to something ignition related like coils or maybe fuel injectors. I don’t have expertise in these items for diagnosis, but I bet if you search this forum, you will find some good suggestions on diagnosing coils and fuel injectors. I suppose you have one more variable, which is the fuel pump maybe getting hot and not pumping as effectively - which can happen on any other motorized machine, I suppose a seadoo is no exception. But I would personally be leaning more towards coils that get hot and the resistance changes to create a poor running condition when hot. You seem to be losing one cylinder. It wouldn’t be a bad idea to maybe do a compression test too, just to eliminate any engine issue, since this is a new ski to you. Hopefully this is contained to one coil or one fuel injector. Good luck!

 

[Digdog]

When you took or take the plugs out what did they look like? Were they all the same color? Were they the right color? Were any of them rusty? Did any have water on them? Start there first, let me know so we can help you eliminate one thing at a time and see if it's the engine or mechanical. You could send us a photo of them if you are unsure, keep them in order of removal so you know which cylinder/plug is which.

 

[fizzman911]

Thanks for all the reply’s. So to give an update I am still having the same issue. What I have to do is not allow the ski to idle for more than 2-3 min. If it starts to act up it starts slowly but I can tell. I give it a bit of throttle and increase the RPMs and it gets better. So I just always give it a bit of gas. I can still idle but I can’t allow it to idle for too long or it acts up. Once it starts vibrating and running rough it gets worse and worse. The whole ski will vibrate and shake. Then I just know to give it gas for about 2 min and it will reset it back to normal.

Plugs all looked the same. But I have never just turned off the ski when it starts acting up. I can’t get it to act up outside of the water because it needs to run for a couple of min and I don’t want to damage the engine.

 

[Randyjspc]

Thanks for all the reply’s. So to give an update I am still having the same issue. What I have to do is not allow the ski to idle for more than 2-3 min. If it starts to act up it starts slowly but I can tell. I give it a bit of throttle and increase the RPMs and it gets better. So I just always give it a bit of gas. I can still idle but I can’t allow it to idle for too long or it acts up. Once it starts vibrating and running rough it gets worse and worse. The whole ski will vibrate and shake. Then I just know to give it gas for about 2 min and it will reset it back to normal.

Plugs all looked the same. But I have never just turned off the ski when it starts acting up. I can’t get it to act up outside of the water because it needs to run for a couple of min and I don’t want to damage the engine.

I have the same issue with mine same year and model. I believe it’s a fuel issue loading up in one of he cylinders at idle which could be a slightly blocked injector try removing them and cleaning and testing. That’s my next option. Let me know how it goes.

 

[fizzman911]

Since it’s not a spark or air issue I was leaning in an injector or fuel pump issue. The other day a started getting the vibration issue and took the seat off while going in circles and took off the wires to each injector to see if I could fine what cyclindar has the issue. I could not find it. Every time I took the wires off the motor would be extremely rough. Much worse than any vibration issues I have. I will need to try again next time I am out. But I am leaning towards fuel problems.

 

[Milehighguy303]

Your disabling coils one at a time was a great idea, and it seems you had a noticeable difference when each coil was disabled. I would definitely replace all the injectors next, and if no improvement, the fuel pump. It does seem to be more of a fueling issue at this point to me.

 

[Rikky001]

Before replacing anything I would measure fuel pressure first, you can buy a cheap manometer for 30 USD.
If the engine works fine at higher speeds than your injectors and fuel pump are fine.
Idling is controlled be the ECM so look first at this, check, clean all connectors and grounds.
Sometimes ECM fail like the thing you have. Before replacing anything I would buy a Candoopro or find a friend who has it, so much more easy to pinpoint an issue.

 

[mikidymac]

You can also send the injectors out for cleaning and testing instead of just blindly replacing them.