Evinrude RPM loss at WOT

[TC123]

I just bought a fish hawk with a '96 90HP evinrude on it. Used it several times with the RPM's running at 5500 WOT. Motor ran great. Recently, the RPM's starting dropping on WOT (4800-5000) and the motor ran rough in low RPM's. I put new plugs in it (the old ones looked pretty bad) and put some stabil in the gas. The motor idles nice now - and the RPM's went up to 5200. I'm curious what the problem is now - I don't think it's the carbs, as it is idling good again after the new plugs. Would a slight clog in the fuel filter cause this? I would have thought a clogged fuel filter would be much more noticeable than a loss of a 300 RPM's.

[Surface Tension]

Did you use the recommend amount of stabil or maybe you went over a little for good measure? Whenever you add anything to the gas you can usually expect to see a loss in performance to some degree. 300 RMPs isn't much when you consider all the variables. Load, trim, weight distribution, gas additives and so on.

See what happens after a few times on the water. About the stabil, use it only if your not planning on using the boat for extended times and only at the recommend amount.

[TC123]

good point. I did use very close to the exact amt (depending on how much gas I had in the tank, etc.). So, I don't think I went over board on it...

I'm thinking now it is the difference in water temp now vs. earlier in the year.

[marine_man]

It likely isn't the change in water temperature.. your motor has a thermostat that holds it at a constant temperature.

marine_man