Took the boat out for memorial day weekend and went onto plane no problem. Took the boat up to about 4700 RPM’s and it was like something kicked the throttle backwards. Shut the engine off, tilted up and looked to make sure nothing in the prop. Went back upto 4700 RPM’s and nothing. Next day, it did the same thing once but then was fine afterwards. Is this the start of a spun hub maybe? Any ideas what else it could be? Not sure if I described it right, but felt like lost all momentum forward but the motor was trying to but couldn’t.
Yamaha 200 engine. Motor is only a year and half old, just over 100hrs and just got the 100hr service done on it.
Didn’t think of Cavitation. I’ll have to do some research on that and see what I can figure out. Someone else messaged me and said to take a punch to the inner and out hub and run the boat again in the water and if they don’t line up then its a spun hub. Otherwise it’s something else. Thanks all for the ideas.
The best way to describe a spun hub is like a slipping transmission. The motor is turning and making revolutions, but the inner hub is spinning inside the prop…so all bark and no bite basically. It will idle in gear as the torque isn’t enough to make the hub slip.
that doesnt sound too much like a spun hub. are you saying the RPMs DROP when this happens, or the RPMs stay the same/go up but speed goes down? i would start by pulling my water separator and looking for any water.
Proline 201WA
Aloha 24ft pontoon (LooneyToon)
Old Town stern with 7.5 johnson
Yeah the RPM’s don’t go up. I hit 4700-4800 RPM’s and can’t take it any higher. The motor makes the sound like it’s trying to go but something is kicking/maybe slipping. Going to take it to my boat mechanic and have them hook it up to the computer and see if anything comes from that. I’ll post when I find out what it is finally. Thanks all for the advice.
try getting a 6 gallon portable fuel tank with new fuel line/primer bulb. hook it directly to your motor and then go out for a test drive. that will eliminate any fuel issues you may be having outside of the motor itself.
Proline 201WA
Aloha 24ft pontoon (LooneyToon)
Old Town stern with 7.5 johnson
I had a similar issue with my 250 Verado. First, they changed the coils. That didn’t fix it. Then they said there was a trim indicator on the motor and another in the shifter. If either trim indicator sensed that the motor was over trimmed, it would kick it back into limp mode so as not to harm the motor from over-revving. If a trim indicator was going bad, that would explain the loss of power and then it would go again. FINALLY, they took my boat out with a computer connected to the engine. When the motor went into limp mode and everything was OK, they determined that the computer was defective and sending bad signals. They replaced the computer on the motor and all is well.
I had a similar issue two years ago with my 75 mercury, I could only get about half throttle and the RPM’s would climb and I would lose speed. I took the prop to Skip’s III Propeller Services and he said yes my prop was old however; I caught the prop either right before it was going to fail or I had an issue with my water pump. He told me that if my water pump does not cool the engine properly it would cause the prop to heat up from the hot exhaust and spin on the hub. I had the hub replaced, prop balanced, replaced my water pump, and it’s been fine. He said typically that when a hub fails, it fails.
Please let us know what the problem was once you get it figured out.
In my experience, a spun hub means you can get all your throttle but no traction. If you are losing RPMs then its likely a fuel issue. Could be water in the fuel or a clogged injector(which has happened to me and was very similar to this situation). First I would pull the fuel water separator and see whats inside, then check VST for debris and clean injectors.
You may even want to pop the cowling off and push the throttle to see if you can get to WOT on the motor. Maybe the linkage has loosened.