Lost Rpms

[South FLA]

Went fishing earlier this week and noticed I lost about 600 RPMs as I was coming out of the hole and about to trim up to run at 5500 RPMs, from then on it was a dog getting out of the hole and would max out at 4900 RPMs @ 49-50 MPH. Engine idled fine and seemed like it ran great.

I first I thought my Powertech cushion lock hub slipped, but after asking my mechanic friends and dad, they said it was an combustion or fuel starvation problem. So I tested the ignition wires using jump tester, changed out the spark plugs (was about to since I was coming up on 50 hours), performed a Seafoam decarb by spiking the gas with 2-3 ounces per gallon while on the muffs, check/drained and re-primed recently replaced 10 micron fuel filter,and replaced the prop with my backup prop which usually spins at 5800-5900 RPMs @ WOT. Went down to the local C-18 canal to test. Out of the hole I was jack rabbit quick, but could only muster about 5200-5300 RPMs out of the top end. This frustrated me cause the engine was lively and reacted quickly to throttle inputs and shot out of the hole. So I ran back to the ramp and back up again when a slight miracle took place, while running WOT I felt like someone put a nitrous shot in while I wasn't looking my RPMS climbed to 5900 and my speed went up to 59! Hole shot was incredible, best since owning the boat! Can't wait to put my regular higher pitched blueprinted prop to see what she'll run.

So what's your take?

I think I might have had some type of obstruction that cleared and the "extra" performance came from the new plugs and decarb. Father says I could have had a bad batch of gas, but I am using the same gas with the Seafoam spike, 2-3 ounces per gallon. As a side note, I run about a full tank through my motor once to twice a month and always use fuel stabilizer. To be safe I replaced the fuel line and bulb from the deck up to the motor with the new EPA approved marine fuel hose by Trident Marine yesterday.

[Sfritr]

sounds to me like you had a small obstruction. Then, when you freshened up the lines, carbs etc. you loosened the obstruction and it cleared. I am in need of cleaning out and replacing my fuel line and bulb as well. You may have just pushed me over the edge.

Congrats on fixing it yourself.

[Dwight Hottle]

Does sound like a cleared obstruction. Glad its fixed because winter is coming if you know what I mean.