Loss of Power Merc 30

"I have a merc 3.0 and am runn

"I have a merc 3.0 and am running wot(4800rpm) and going 32mph when I should be 42 by the specs but have gone 38mph.
I also have rough idle,and stall on powering down, carb rebuilt last year. Also when in the driveway with the ears on and running 4000 rpm there' lots of white smoke.
Are alll these issue tied together"

""in the driveway with the

""in the driveway with the ears on and running 4000 rpm"

You may have done her in @ 4000 RPM. ONE BIG NO NO! Limit RPMs to 1500 on muffs.


"and running 4000 rpm there' lots of white smoke."

It's either steam from the high RPMs or water is being ingested and burned.


"have rough idle,and stall on powering down, carb rebuilt last year"

Perform basic tuneup to see if idle improves. Carb may need reworked or at least adjusted."

"First 4000 rpm on muffs not g

"First 4000 rpm on muffs not good idea,
White smoke or more likely steam (4000rpm)
4800 rpm seems a little high and with loss of speed and not rpm hints at a bad prop hub.
Sounds like carb issue if stalls on throttle down. Is boat bottom clean? has the hull taken on water lately? May be water weight. When was the last full tune up done? Also service fuel system to include filters, inlet screen at carb
,check valve at tank, tank vent line clear. also after full tune up check base timing and that it advances fully by 2300 rpm or so.

Kurt"

"thanks,
Guy

White smoke,

"thanks,
Guy

White smoke, where is the steam coming from?
Could bad gas also cause all my symptons?

Kurt S boat bottom clean, the hull may have taken on water due to heavy rains,vent line is clear,full tune up was done last year but I'm not sure of timing,I'll check check valve.

Bad prop will I'll check it out, Occasionally I also have to add fluid to the lower unit, could this be slipping?

I also had to clean my flame arresstor because it had a heavy film of oil on it."

the steam comming from the exh

the steam comming from the exhaust can be explained like this.. If you have ever put a couple drops on water in a hot fring pan you get a little steam. which is probably whats happening at high RPMs in your boat. when the RPM's drop (on the ears)it is able to put more flow from the ears on the hot exhaust... hope this makes since... And promise me and everyone else on this forum??? Stay under 1500 RPMs on the ears.. if you value you boat

Thanks for explaination about

Thanks for explaination about the steam. I may have not fixed my problems but at leat I learned not to rev boat with ears on.
Made an appointment with mechanic so that I can be another 300-500 lighter in the wallet but will be able to sleep at night.