2019 QX 25 Performance Issues

[mdowning79]

Hi all, I am desperately hoping someone can shed some light on some grave performance issues that I am having with my 2019 QX 25 with a Yamaha 300. Currently the boat will not go more than 22 mph at 5600 rpm, this is way below the performance level I was expecting, and along with the poor performance, it is getting extremely poor fuel economy. The boat has a 15 3/4 x 15 saltwater series prop, which Bennington confirmed is the correct one. Things I have confirmed, all pontoons are dry, the lower unit is brand new in the last 50 hours (performance issues present before this), compression on all cylinders is good, fuel system checked and operating as designed, and there are no codes present. Any insight into this very frustrating issue is greatly appreciated.

 

[Jack M]

What do you consider poor fuel economy? My Verado 250 burns 22 GPH WOT in sport mode 28 in quite mode. Are your toons clean ?
You mentioned they are dry .
Also check with Ken at propgods.com.
He's gotten more than a few members here dialed in with their prop.

 

[LaurencetheAdventurer]

I think more data points would be helpful: Is this new to you and this is how it always performed, or it previsouly was faster so when you stated "Currently" this is a new event? The QX is a heavy boat - I could not find anyone that listed their performance on LIST YOUR SPECS HERE thread, but I did find a few Y300 on larger Bennys (not QX) - they were running in the 40's at 6000 rpm. YOUR low rpms suggest slippage - but I can't imagine that they replaced the lower and did not replace the hub - but might be worth a check (look at invoice and/or pull the prop). Jack has solid suggestions: Clean Toons / check with Ken. If you got used, it could be the prop is not balanced / properly tuned - I had a prop repair that looked great, but was not balanced and lost about 3-5 MPH.

 

[Vikingstaff]

Ditto the above two comments. Very curious on cleanliness of pontoons. Scum on them totally cuts down on performance in ways like you are experiencing. As said above, a bit more data points needed, and there are other possibilities too as already mentioned.