12mph Loss of Power

[Paulywog0667]

My 71-72 hydro-electric was running good all day. My wife and I trolled for roughly 3hours(2 walleye). Heading back in I gave throttle and it picked up to roughly 10mph. Then revved and lost power as in getting to plane. Maybe like it cut power if the prop regrabbed water after revving up. I throttled back and ran fine. Brought it back up and same thing around 10mph. Held 10mph back to the dock. I have an extra prop, power pack and ignition coils. Does that seem the basic either or? It didn't stall and after off at the dock I restarted it after pulling off the fuel hose. Didn't seem to rough start. The side control looks like it has a heat alarm. Is checking the prop bushing something to mark and reach speed. Odd since it was right after trolling at idle for so long.

The power pack wouldn't cause a jump in rpms if going would it?

 

[jimmbo]

Trolled for 3 hrs? I suspect a Fouled Plug(s)
Did you check for Weeds?
which motor are you referring to? In 71 - 72 the Engines were 50hp, 60hp, 85hp, 100hp, 125hp

 

[F_R]

I'm having trouble reading the question. Are you saying it revs up but boat won't go faster than 10 MPH, as in "slipping"? That would be a spun prop hub or cavitation caused by weeds or whatever.

OR are you saying it won't even rev up? That would be an engine problem involving anything from fouled plugs to ???. Don't be so quick to fall into the old "It's always the black box" way of thinking.

 

[racerone]

Try another prop on your 50 HP motor.----Or mark hub and prop and test run.