Engine randomly "revs" and doesnt pick up speed at WOT?

[rtpassini]

Sometimes if I go WOT it feels like a slipping clutch or tranny would. i can hear the motor rev up (I havent watched the tach to actually see if it does), but i dont go any faster for a second or two. generally its around 20-25 mph. it doesnt slow down or anything. No clunks, weird noise, etc. Im not sure if this has to do with the water, or if theres a bigger issue? I dont know enough about boat motors or issues similar to this. Any direction as to what this is would be great.

 

[racerone]

Re: Engine randomly "revs" and doesnt pick up speed at WOT?

Try another propeller.

 

[Chinewalker]

Re: Engine randomly "revs" and doesnt pick up speed at WOT?

Could be as simple as some slight ventilation due to motor too high on transom or tilted too far out. Does the motor have power trim?

 

[rtpassini]

Re: Engine randomly "revs" and doesnt pick up speed at WOT?

Could be as simple as some slight ventilation due to motor too high on transom or tilted too far out. Does the motor have power trim?

I should clarify that after a second of this or so, it picks up and accelerates as normal

The prop is brand new.

It does have power trim. To me it almost seems as if it hits a pocket of air or something, no resistance. i havent tried raising it to see how it reacts. i did try throttling down right when it happened and then accelerating but didnt notice a big difference.

 

[Chinewalker]

Re: Engine randomly "revs" and doesnt pick up speed at WOT?

The "air pocket" you describe is the ventilation of the propeller. Raising the motor will likely make it worse, not better. The motor may need to be lowered a bit on acceleration. If that doesn't do the trick, then it may need to be lowered on the transom, if possible. Do you have a pic of the antiventilation plate in relation to the bottom of the boat?

 

[midcarolina]

Re: Engine randomly "revs" and doesnt pick up speed at WOT?

Do you happen to have a bolt on hydro foil on the av plate?

 

[rtpassini]

Re: Engine randomly "revs" and doesnt pick up speed at WOT?

Do you happen to have a bolt on hydro foil on the av plate?

I can grab a pic

and yes, i do have a bolt on hydrofoil. like this Boater Sports 52620 2-Piece Hydrofoil - Boater Sports 5-52620 - Skeg Guards - Propeller Parts & Accessories - Propellers - Boatersland Marine

 

[midcarolina]

Re: Engine randomly "revs" and doesnt pick up speed at WOT?

Ok....... that is what is causing the ventilation...... the foil is causing extra lift of the stern........look into getting trim tabs.

 

[rtpassini]

Re: Engine randomly "revs" and doesnt pick up speed at WOT?

well thats good to know. so its nothing to worry about really. just more of an annoyance to some. it doesnt really bother me.