TOPIC: 1000 Thunderbolt looses power at full throttle

Boat newbe -

I just purchased, fourth owner, a 1968 16ft Glastron Avalon with a 1969 1000 Mercury Thunderbolt 100/hp engine. As I slowly apply power the engine looses power after 1/3 to 1/2 throttle but it doesn't die or stall out. I can only describe it as the engine sounds like it is sucking air or over-revving.

I spoke with the previous owner and he said that possibly spraying carburator cleaner could resolve the problem.

My question is, could carb B12 cleaner help and if so how should this be applied.

THe engine sounds good at startup and doesn't die it just simply looses power and will not get up on plane.

Any help is greatly appreciated.

See post below,,,Dam Maintainice Now What,,They may lead you in the right direction.It does sound like a fuel issue,diaphram,fuel line clogged up,carb jet with crap in it.Someone with more knowledge will chime in,response is usually a little slow on a weekend in the summer.

try backing out on the idle jets 1/8-1/4 at a time.

Sucking air? are you saying that the prop isnt catching any water? engine is screaming? just at a glance I would look at your prop, give us some more clues and PICS!....NEVER spray carb cleaner in a running engine,all lubracation comes from the oil in the fuel,spraying carb cleaner reduces that oil and bad things happen. get us a pic of the back of the boat-engine down and a prop size or pt#

excerpts from your post "engine runs fine sounds like its over reving while trying to get on plane"....

I wouldnt mess with the carbs yet.......do you have a spare prop to try, sounds like you may possibly have a spun prop hub from what you explain

now there's a thought, I had a spun prop on my rinker-scott set up, I had a horrible time turning that boat but it would come out of the hole just fine......we need to see the prop.

I agree. Sounds like a spun prop. I had one on my fat fifty.

I agree with Mr. 88, I would guess that it is a fuel pump issue with the diaphram.

robinr01

Im confused.......motor is screeming but its been suggested that the fuel pump needs rebuilt? or its a spun hub on the prop......2 very different repairs for 2 very different problems. , wheres jpkuhns?

jp
Before you rip into it, put a known good prop on it and take it for a spin. Then report back with what it is doing.

All...

Thanks for the help. Finally got it out and put a borrowed prop of same size and pitch and worked great.
So now to purchase a new prop.

Thanks for all of the help!

Glad you got it sorted out.
Put a picture of that beast on here, with you grinnin'!
Neil