2015 Scarab 195 HO Impulse runs slow at only 6000rpm

[MichaelN]

Was hoping someone could help steer me in the right direction as there are NO Scarab mechanics around my area.
I have a 2015 Scarab 195 HO Impulse with about 245hrs. Recently I have have been experiencing the boat being very sluggish and running rough during low speeds.
Typically I was able to run the boat around 38-40 mph at top speed. Now it only runs a top speed of 24 - 26mph with WOT at 6000 - 6100rpms. Then at lower speeds, closer to no-wake speed the boat runs pretty rough, almost like it is missing. At WOT the boat is smooth, just not cruising at its full potential.

Recently the oil pressure sensor was replaced due to a code and the boat running in lump mode. This fixed the limp mode issue, but immediately after putting the boat in the water, the recent sluggish performance was noticed. Under the suggestion of a mechanic, I had the spark plugs replaced, but no difference.

It almost feel like there is no boost as I would typically hear and "feel" the supercharger kicking in.
So, I feel like it is a supercharger issue, but wanted to get some advice from fellow Scarab folks to see what possibilites there are to explain this. Is there a good way to "self diagnosis" this problem?

The last time I took the boat into the shop (3hr drie away) with a small oil leak, they replaced an o-ring and a small plastic valve. The parts...$197. The labor...$1900. So as you might guess...I am not eager to put the boat in the shop right away without at least some idea of what could be going on.
I am trying to sell the boat, but want to be honest with anyone that might want to purchase it. BUT if the fix is relatively inexpensive I might consider keeping it.

Any ideas and/or help would be greatly appreciated!!

 

[Sidarousmg]

a couple of questions: has the supercharger ever been rebuilt? if so, by whom and how long ago? which engine do you have, the 200 or 250 hp?

 

[Scarabscott]

I have a 2019 scarab 300 and had similar issue, turned out to be the intercooler has sound deadening mat on top of it and its wedged in there pretty good, well the matt got wet over time from water like a soogy sponge and that ate at the aluminum intercooler causing a whole/leak causing the loss in boost.

 

[MichaelN]

I have a 2019 scarab 300 and had similar issue, turned out to be the intercooler has sound deadening mat on top of it and its wedged in there pretty good, well the matt got wet over time from water like a soogy sponge and that ate at the aluminum intercooler causing a whole/leak causing the loss in boost.

Thank you for the response. I don't see any leaks at all...oil, water, coolant, etc. So I am not sure if that is the issue, but I will certainly check that.

 

[MichaelN]

a couple of questions: has the supercharger ever been rebuilt? if so, by whom and how long ago? which engine do you have, the 200 or 250 hp?

The supercharger has never been rebuilt and the engine is the 250. This is why I am leaning towards the supercharger.
The sad part is that I have NO ONE in my area (Indiana) that can work on Scarab boats, so I wanted to try and do as much self diagnosis as possible before driving it 4-5 hrs to drop it off for service.

 

[Luc Lafreniere]

I'd definitely have that supercharger rebuilt (or purchase the new "maintenance free" (spoiler, not actually maintenance free)) supercharger.

Otherwise, have you inspected the pump at all? Based on your description, I'd start there.

 

[blthlt]

I'd definitely have that supercharger rebuilt (or purchase the new "maintenance free" (spoiler, not actually maintenance free)) supercharger.

Otherwise, have you inspected the pump at all? Based on your description, I'd start there.

I wouldn't drive that boat much until that supercharger is checked/rebuilt. It can come apart and do massive damage to the engine.

 

[Sidarousmg]

+1 for the supercharger rebuild. at 250 hours and 10 years old, it very well may be your problem, and they have a history of grenading if not maintained. you can do it yourself, it's about 2-3 hours to remove it and send it out to be rebuilt, another 2 hours to put it back in. costs about $5-600 parts, labor, and shipping. one other thing you could check on, since you have the 250hp engine, you also have an external intercooler. at least in the seadoo version, they are known to leak and start sending water into the engine intake. checking it is relatively simple, just remove it and inspect, if there is any amount of water inside, you have a leak that could be causing your symptoms and should be addressed ASAP.

 

[MichaelN]

+1 for the supercharger rebuild. at 250 hours and 10 years old, it very well may be your problem, and they have a history of grenading if not maintained. you can do it yourself, it's about 2-3 hours to remove it and send it out to be rebuilt, another 2 hours to put it back in. costs about $5-600 parts, labor, and shipping. one other thing you could check on, since you have the 250hp engine, you also have an external intercooler. at least in the seadoo version, they are known to leak and start sending water into the engine intake. checking it is relatively simple, just remove it and inspect, if there is any amount of water inside, you have a leak that could be causing your symptoms and should be addressed ASAP.

I'd definitely have that supercharger rebuilt (or purchase the new "maintenance free" (spoiler, not actually maintenance free)) supercharger.

Otherwise, have you inspected the pump at all? Based on your description, I'd start there.

So the shop that I normally drive to said that they need to pull the engine to replace the supercharger which is quite expensive in labor costs.
I have never seen the supercharger on that boat (I will look this weekend), but is the shop right or can I truly do this replacement on my own without really screwing something up? I am pretty mechanic and do my own work on my truck, so is it that difficult or do I need a licensed boat mechanic to take on the task?

Also, if I read correctly...the new "maintenance free" superchargers came out in 2017...are these compatible with an older Scarab engine?

 

[Sidarousmg]

you can certainly remove the supercharger yourself, it's a little tight and you need a special wrench/bit, but you can easily get it. PWC muscle is where i had mine rebuilt when i had my old seadoo. they sell the torx wrench that you will need if you don't have it, they also have a step by step video for removing and installing the supercharger. it's on a jetski, but same exact engine. i'm not certain about the compatibility of the "new" superchargers to the older engines, @Luc Lafreniere may know more than i do about that subject.