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2001 Mercury 4 stroke low power

J

John Bravo Zammit

New member
Hi guys,

Got a 14' rib and re powered from a 25hp Evinrude 2 stroke to a Mercury 60 4 stroke
Old setup gave me 30 knots with just me on board

Now with over double the power I'm now barely managing to get to over 4000 revs and am running max 23knots

Load on the boat is
2 people aboard 120kgs (265lbs)
60 liters (16 US gallons) of fuel
engine plus boat is no more than 400kgs (882 lbs)
Prop is an 10"x12"pitch Solas - This should actually be an undersized prop

To add to all of this if I run for more that 5 mins at over 3000 revs I'm getting an alarm and the engine drops down to 2000 revs
Alarm stays on at 2000 revs

Water coming from the back is a steady stream and is not hot to touch
Engine is cool enough to touch

If I turn off ignition and restart the engine will allow WOT again
I tried a larger prop (11"x15"pitch) and the boat just slugged she barely wanted to plane
According to the manual I should actually pop in a 10"x16"pitch

So far have done the following
-made sure cable actually opens carbs to full throttle
-change fuel filter
-new plugs
-fresh gearcase oil
-fresh engine oil


any ideas as I'm now out... really hope I didn't buy myself a lemon :-(

regards

-J
 
What year? Is there some trash stuck on the water intake? When was the water impeller last changed?
 
engine is a 2001 ELPT 60 four stroke
first bought in 2007

Impellor is to be replaced before the weekend and to be tested on saturday

This still does not solve the power issue... can't really believe I'm getting less power out of this engine that a 92' Evinrude 25 DTLE
 
yeah I do... and don't tell me to pop it back... it drinks fuel like there's no tomorrow
Evinrude was 84kgs
Mercury is 104kgs

Boat is rated for 80hp max
Evinrude was fine with just me and a passenger aboard but started to slug with 2+ passengers thus the change in motor
 
ps its 80hp max using the old system (boat is 22 years old)
ie measured at the prop
this should be equal to around 72hp at the shaft with the way engines are rated nowadays
 
To add to all of this if I run for more that 5 mins at over 3000 revs I'm getting an alarm and the engine drops down to 2000 revs
Alarm stays on at 2000 revs
Click to expand...

Isn't a continuos alarm a condition of overheating? Rev limiter is reducing RPMs to save the engine. Are you sure all the plugs are firing? Replace the impeller. Check the compression w/engine warm w/ throttles wide open. Redistribute the load on the boat. Verify the prop is not slipping on its hub. Try a smaller pitch w/larger blades prop.
 
tell me about the 25 I might want it, electric start/pull start, short shaft/long shaft tiller or remote controls, year, etc, location
 
disassembled the foot last night... impeller was in a very good state of repair.. one thing I did notice tho is that the plate was installed upside down and one O'ring was either missing or totally decayed... ie the key hole did not match the hole on the housing

Gonna increase the diameter of the fuel lines this eve as am using the line from the Evinrude and the Merc seems to have a larger diameter hose to see if that solves the power issue

any other ideas will be appreciated
 
Have the 60 HP tested by a shop ( dynomometer or test prop ) to see if is putting out the rated horsepower.-------------There is likely something wrong with the motor.--------Test compression and check spark on all cylinders !!
 
...disassembled the foot last night... impeller was in a very good state of repair.. one thing I did notice tho is that the plate was installed upside down and one O'ring was either missing or totally decayed... ie the key hole did not match the hole on the housing...
Click to expand...

Let's hope that correction solves the contiuous alarm issue and stops the rev limiter from turning itself on and reducing power.

Gonna increase the diameter of the fuel lines...from the Evinrude and the Merc seems to have a larger diameter hose to see if that solves the power issue
Click to expand...

So do I. Good luck.
 
impeller and fuel lines replaced... have a bad water tube seal that may be the trouble with heating as could be losing pressure through that... old impeller was fine changed it anyway including seals and gaskets.. its a bitch that the dealer here didn't have the darn tube seal
looks like we now have 6000revs with the new fuel line... at least on no load.. will keep you ppl posted tomorrow once I trial her

old fuel line 1/8th" new 1/4" so big change :p
 
ok... now I found that the darn throttle cam on carb 4 is broken... the arm keeps popping out of its place... I've jury rigged it by drilling through the plate and the shaft and popping in a screw to retain it... so far so good but not a permanent fix

I've been through the whole service manual and can't seem to find the part available anywhere
Am starting to think that its part of the carb assembly and you'd need to replace the whole darn thing

the exact part I'm talkng about is the one that part that the Throttle CAM (Part# 853585 3) attaches to with a single screw

Anybody got a clue what the part number for this would be?
 
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