2018 G3 CC 18’ - impeller / flanged liner / intake carnage ; also need high elevation tips

[Webberlander]

Hey All,

I made an introduction post about my boat in the new members thread and mentioned I start a separate post for help/recommendations/tips etc.

So first things first, the boat is down on power big time and before I discuss major altitude change, I’ll give a brief background on where this boat, until now primarily was run. It was run almost daily on the lower Colorado River for almost a solid 3 years and if anybody reading this knows that section of River, you know it gets skinny in a hurry with a sandy/gravel bottom almost everywhere. Obviously not good on the jet prop.

Below in photos you will see the carnage I found upon taking the intake, flanged liner and impeller off. NOT GOOD!!! I really tried my best not to allow debris to get sucked up, but it’s bound to happen especially on that body of water. I have ordered a new flanged liner as I know there is no way to salvage the original. As for the impeller, it’s pretty tore up, but I did take the time to try and clean it up before ordering a new one.

What are your thoughts on the impeller? I know that the 1/32” tolerance is very important so am I wasting my time by only replacing the flanged liner? Any tips or comments on what you see before and after?



Impeller After Cleaning it up:



Finally, regarding altitude adjustments. I went from sea level to 7,500 feet where the boat lives out of the water. One reservoir I have visited now twice is at 9,000+ feet. Being a 4 Stroke EFI motor, changing jets certainly isn’t an option. Below is what I’m in the process of doing but any tips, advice etc. is greatly appreciated!!!

• Ordered new Spark Plugs (OEM). *should I gap them different?
• Oil Change (its time anyway).
• Disconnect battery (theory is to reset the ECU/ECM so it can readapt ???)
• Check throttle cable(s) <<< Never done this before but willing to check.
• Replace Water Separator filter
• WHAT ELSE???

 

[Ronnie]

No opinion on most of this but the 2000 eta seadoo boats used mercury sport jet pumps and engines and they offered what they called a rock intake grate that did a good job of keep the bigger rocks out of the pump. Basically the rock grate has twice as many tines and very little space between each time nothing bigger than the space could get sucked up. If you can modify your grate to make it similar you should be able to reduce the damage to the pump, liner and impeller in the future.

 

[TimW451]

I believe you’ll want props with a different pitch. Search the site for “high altitude”.

 

[FSH 210 Sport]

As far as the ECU goes at high altitude… just start the motor and let it run for 15 mins, just start it and don’t touch the throttle, the ECU will use the map sensor, intake air temp sensor and coolant temp sensor to adjust the map to the density altitude you are at.

Spark Plug gap: Run the gap specified in the manual.

As far as the impeller goes.. either get a new one or get that one repaired, you need to know what the rated rpm of the engine is at sea level, then what the wide open throttle rpms are at your location. Once you have that info, then you can approach a company like Impros and have them either repair and re pitch your impeller, or just send Impros an impeller, who knows Impros may be able to source the impeller for you.

 

[Webberlander]

Thank you for the replies. Happy to report the boat is running much better with having done the maintenance listed above plus installing a new flanged liner. I did re-use the impeller after having cleaned it up and I’m able to get over 20 mph which more like it was. When it gets into shallow water it will run 23 - 25 mph.

Eventually I will have the impeller replaced and pitched correctly to the altitude I’m at but for now fishing reservoirs more than rivers, it will do just fine.