New Boater, Engine Trouble with 2016 Scarab 195 HO Impulse, 250 HP

[JoshuaBakerUSA]

Joshua Baker
Memphis, Tennessee
2016 Scarab 195 HO Impulse, 250 HP
mrjoshuabaker@yahoo.com

Good Morning Jet Boaters Community,
I recently purchased a 2016 Scarab 195 HO Impulse, 250 HP with 27 hours on the Engine. Super excited to join the Jet Boater Community! I purchased on December 1st, 2019 and I have taken the boat twice. The first time out everything worked great and I was able to boat at all speeds with no noticeable issues whatsoever. The second and third times out, I have experienced significant engine noise, boat rattle at anything over 4000 RPMs and was not able to enter on plane. It seems like the Scarab is not able to increase its speed over 10/12 mph. I have attached two video Youtube links to better describe the issue. I am a new boat owner and not very knowledgeable about engines and turbo chargers etc. in general. My local marine center has limited experience servicing Scarabs/Rotax and I was hoping to assist in the diagnostic area. Thanks again for any help that you may be able to provide. Unfortunately, both the engine and the boat are now outside of warranty. I am the second owner of the boat. Thanks!

Videos (cut and paste into browser)
2016 Scarab 195 HO Impulse Engine Trouble Video 1

2016 Scarab 195 HO Impulse Engine Trouble Video 2

Joshua Baker
Memphis, Tennessee
2016 Scarab 195 HO Impulse, 250 HP
mrjoshuabaker@yahoo.com

 

[Luc Lafreniere]

Sounds like you have debris in the pump. You have to look in there while out of water and clear any debris like twigs, shells, pebbles. The smallest piece can have a huge effect. I don't know how much debris is in the water you run, but otherwise be careful not to run the engine in shallow water especially when idling. You can suck up all kinds of things.

 

[JoshuaBakerUSA]

Joshua Baker
Memphis, Tennessee
2016 Scarab 195 HO Impulse, 250 HP
mrjoshuabaker@yahoo.com

Thank you Luc. My apologies for the remedial question, but I’d the pump something that I can clean out myself. If you could point me to info on how to clean out the pump I would greatly appreciate it. Thanks again!

 

[Luc Lafreniere]

Definitely. Typically, just use a flashlight and look inside the grate. Super long needle nose pliers (you can buy them on Amazon), a piece of long enough rebar, something to reach inside and pry out whatever is stuck. Careful not to damage anything. It's very important you do NOT try and remove the grate. Those bolts are not designed to be removed apparently. So don't try and remove that. Do whatever you can to get the debris out otherwise. If you can't remove it at all, then the easiest thing is to remove the bucket, nozzle and pump from the rear. This sounds scary, but it's incredibly easy to do. Talk to me if you need to do that first. Takes about 20 min to remove it and another 20 to reinstall it.

Sometimes it's not stuck and it's just loose debris rattling around. So there's a "manoeuvre" you can use while on the water to eject potentially loose stuff. If your boat is still in the water, you put it in reverse as high speed as possible (the limiter will not let you go too fast), once at top speed, you SIMULTANEOUSLY kill the engine (use the emergency pull cord, it's the fastest way) and stick it in forward WHILE turning the steering wheel hard right or left. So three things have to happen at the same time. Kill engine, forward and turn hard. This will stop pumping water, move the reverse bucket up so water can flow backwards through the nozzle and pump and the turning moves the water in different directions to try and clear the debris. The debris will often flush out of the grate and then you're good to go. Don't be afraid to this manoeuvre multiple times. Sometimes it works on the first try, other times it takes 10 tries. If after that it doesn't work, now is the time to pull out the boat.

And of course, avoid debris in the first place. That's the main thing to do. #1 are ropes. Lol EVERYBODY seems to underestimate ropes. If you go over a rope with the engine running, you are screwed. You have to kill the engine. Careful with new drivers... Happens all the time on the forum. Lol

 

[JoshuaBakerUSA]

Thank you! This is incredibly helpful. Please see the photo of the rock wedged in the impeller. I was able to knock the rock loose but I could not collect it. I am attempting to vacuum it out now. Thank you so much for all of the advice and detailed instructions. Unfortunately, I did try to remove the grate and I encountered the bolts that you were taking about that are not able to be removed. I have retightened the bolts back into the neoprene buffer/gasket, so I hope I will be okay! Thank you again! I will be out for a week but will let you know as soon as I am back on the water! Thank you!

 

[BobJohnson]

@JoshuaBakerUSA you don’t want to remove the grates. If need to get something out of impeller/pump much better to remove pump assembly. Please see video for step by step. Not my video but from a guy on the vortex Facebook group (same pump as your scarab).

 

[Luc Lafreniere]

@BobJohnson That specific is a great one for the "how to".
@JoshuaBakerUSA The forum is here for this. It's been extremely useful to me over the years. Make sure to look through old posts, there's a lot of great info. And glad you were able to identify the problem quickly. Hopefully you can get it out.

 

[JoshuaBakerUSA]

Joshua Baker
Memphis, Tennessee
2016 Scarab 195 HO Impulse, 250 HP
mrjoshuabaker@yahoo.com

Fantastic, fantastic information from @Luc Lafreniere @BobJohnson and others. Thank you so much. That video on How to Remove the pump and impeller is awesome. Thank you very, very much. Rather than chance it, I will work very slowly and remove the pump and impeller to remove the stone since I was not able to vacuum it out. Thank you again!

 

[JoshuaBakerUSA]

Thank you for all of the instruction. I followed the video step by step and removed the shell/stone/ceramic piece from the impeller. It appeared to be wedged perfectly between the fins and thrust cylinder. Thank you again for all of the help. You all saved the day. Final question: the jammed debris seemed to be so wedged in that the impeller could not move at all. Is this possible? The boat was able to move but no more than 8 to 10 mph regardless of RPMs. Can a jet boat move without an impeller spinning? I know a remedial question, but is there another source of small propulsion from the engine without the impeller spinning or does it always spin? Thanks again!

 

[Luc Lafreniere]

Nope. It probably spun, but slowly. Did you notice any damage to the wear ring (blue plastic surrounding the impeller)? Sometimes when stuff can get stuck, it can gauge the wear ring. If there's any significant gauging, it's important to replace the wear ring. The power of the boat comes from how tight the impeller is to the wear ring. Any gap between the impeller and that ring will cause cavitation and you'll have poor performance. You'll lose top speed and hole shot. My boat comes out of the water here and there and when it does, I have a quick look with a flashlight to see if there's any damage. If you don't suck up anything, it can last a long, long time. But if you do, then you should definitely keep a close eye on it (and of course, avoid it). The impeller is also important, so watch for any damage, nicks, etc. that can also cause problems. Depending on how badly damaged it is, you may be able to file it down to clean up the edge. But if it goes too far, then the impeller needs to replaced.

Now that you know how easy it is to get to it, at least you know that if anything like this happens, you can deal with it.

 

[JoshuaBakerUSA]

Thank you again to everyone on the forum and especially Luc Lafreniere for the superb guidance!

 

[Barry Ceci]

@JoshuaBakerUSA you don’t want to remove the grates. If need to get something out of impeller/pump much better to remove pump assembly. Please see video for step by step. Not my video but from a guy on the vortex Facebook group (same pump as your scarab).

Bob,
My Scarab 195 picked up some debris and was cavitating at 6 mph. I began by attempting to remove the grates hopefully to clear the alleged debris. Once I learned I was unable to remove the grates, I searched the forum and found the video you posted on removing the pump. I executed this approach which was relatively easy. I found a small stick jammed between the impeller blades, put it back together, launched the boat and it runs like new. Just want to thank you for this posting; saved me substantial time and money trailing it up to the dealer, which was my only other option.
Barry