1987 90 HP VRO Prop or something else?

[swab]

I have a 1987 90HP VRO on a 24 ft Sylvan pontoon boat. Here is the problem. I can't seem to get it to run over 4000RPM (unless it cavitates). The prop is a 13¾ X 14. It will not get the boat over 14MPH (on GPS) with 2 adults. Anyone have any ideas?

 

[Dhadley]

Re: 1987 90 HP VRO Prop or something else?

Welcome!!<br /><br />That was always the problem with some pontoons. Thats why they made "special" pontoon props. They have lots of cup to help grab water. There can be some very aerated water around the gearcase on some pontoons.<br /><br />Lets look at the tach first. What brand is it? Make sure its set on position 6.

 

[swab]

Re: 1987 90 HP VRO Prop or something else?

I will go down to the marina and check that tonight. Another thing I forgot to mention was that sometimes the tach seems to just drop to "0" then jumps back up to the correct (I hope) RPM's even though the RPM's are not fluctuating. I will take a look at the brand and position setting, is there anything else I should check while I'm there?

 

[Dhadley]

Re: 1987 90 HP VRO Prop or something else?

Just the overall condition of the prop. If it was doing this even when the prop was new thats one thing. But if it used to be OK and slowly got this way we might just be looking at reconditiong the prop.<br /><br />Start at the hub and feel the cup on the trailing edge. Follow it along the blade and see where it stops or runs out. It should go at least 1/2 way around the tip. Depending on what brand and style it is. That would help to know too.