I previously posted this in the LT section but got no hits:

I have a 24hp Honda beavertail longtail. My RPMs at full throttle are 4000 but in the water at full throttle are only at around 3000. I was expecting more like 3600 or 3700. What could be the problem? The hull of my boat is hooked pretty bad and I can’t really get up on plane, I don’t know if this is because of the hull or because of the RPMs not being high enough when the prop is in the water. Thanks for any help.

I'm not a mechanic by any means, but I know fuel issues can cause it to have a lack of power under a load. I would think it would still turn the proper loaded rpm's if everything is right on the motor, despite what the hull is like. Might try helping the fuel delivery with an inline pump or new filters, or even get the carbs looked at. If your prop is over pitched or too big for the motor, you could have that problem too. Ihave this same motor, and mine would bog down really bad under a load, but run fine out of the water, it was fuel delivery. Put an external pump on and solved it. Another thought, get a clear fuel filter so you can see if you are getting good pressure or not. Before the changes mine was always running dry, after a carb rebuild and fuel pump the filter is full all the time.

If you are having lack of power under load you need to check for fire on both sides. I was having a real simular issue and it ended up being the coil pack on the right side. Problem was it only did it after it got warm and was under load.

Hope this helps.

How do you test for one side firing under load (just run under load and see if both sides are hot?) and how do you isolate what the problem is?

I have the same motor and have had similar fuel delivery issues due to the fact that the pump is on the motor and the tank is 18' away in the bow. These pumps are not designed to pump against that kind of head. What kind of pump do you recomend installing? I though of an electric, but I am worried about bowl overflow without some type of regulation or return line.

Easiest way to test your coils is to use an inductive timing light, simply hook it up and watch the light, if it is not a steady pulse you have issues.

It is my opinion that beavertail over props this motor from the factory. It is originally equiped with a 9x7 prop to which I have had poor performance. I have installed a 9x6 from Ron Hill marine and my boat will now plane out at 1500 rpm!

I no longer have the boat/motor combo, but I don't think it had anything to do with the motor and had everything to do with the condition of the hull.