No power underload
Hi guys
while I am waiting for Arthur page to come out in a fortnight, anyone able to shed a bit of light on what is happening with my outboard.
I have a 2008 115hp Mercury optimax 2 stroke, and currently I have no power under load only goes at 6.5 knots, I have changed fuel tank replaced water separator filter, fuel filter new fuel hose and primer bulb put in 3 new spark plugs but still no power underload, perfect in driveway on the muffs but not on the water, I took prop off found a bit of line on shaft also pretty rusty behind prop (any thoughts there)I changed gear oil it was not milky it was dark oil but smelt burnt. I thought it might have gone in guardian mode but I have no alarms or faults on my smart gauges any thoughts while I am waiting for Arthur.
"If we all fish for the future now there will be fish in the future"
big john
Posts: 8749
Date Joined: 20/07/06
Bush
Not sure on a motor that size, but I had a 15hp evinrude way back when that slipped the rubber bush in the prop due to overloading. As force built up with speed, the rubber bush would slip and it wouldn't go any faster even though the motor was revving as normal.
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Marineboy
Posts: 842
Date Joined: 14/03/14
Optimax
Got a mate who had a similar issue with an optimax, it was the coils from memory.
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Shark1
Posts: 1086
Date Joined: 21/05/12
Just Props can check if it
the problem u describe, if the motor is getting full revs i m unsure form your post - does it get full revs on water - it can only be the gearbox or prop- if gearbox u would have no drive
sounds like big john said - slipping bush in prop
it looks as if the grease in the bush has overheated- i ve seen simular on slipped bushes before
not the most expensive problem to have and an easy fix, takes like 5 mins
little johnny
Posts: 5359
Date Joined: 04/12/11
Agree with first comment
If it revs out and doesn’t pick up speed.
scotto
Posts: 2470
Date Joined: 21/04/08
injected?
is the motor injected, or carby?
I had a similar issue with my 4 stroke 140 suzuki. it struggled to get above certain revs, and I could only get 6-7 knots out of her. turns out the water seperator filter had a lot of water in it, and water made its way past the inline fuel filter, and into the high pressure fuel filter and high pressure fuel pump. these are the last stops before the injectors, and stopped the boat from going into high revs.
I had to disassemble the motor, manifolds, fuel lines, filters, etc and replace the HP fuel filter (which was only $100). I cleaned out the HP fuel pump whilst I was there, as its an absolute C**T to get back into later on.
I reassembled everything, and got better performance out of her thane ever before!
sea-kem
Posts: 14972
Date Joined: 30/11/09
Mate had a similar issue
Mate had a similar issue with his 30 Yammy 4 stroke with carbs. Plenty of revs with no load, soon as you put it into gear no power. Had a full rebuild of the carbs and it was a power house.
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tiimmbo
Posts: 695
Date Joined: 16/08/09
I had a 90hp 2 stroke
I had a 90hp 2 stroke mariner years ago that did exactly the same thing. Would only do it on the water under load. Was the coils. Cheap fix and can DIY
little johnny
Posts: 5359
Date Joined: 04/12/11
With rust on link
Doesn’t look like prop issue . Prob is coils ?. Need big bank balance when dealing with optimax . If you can figure out yourself way cheaper . Great motor in there day
surge
Posts: 212
Date Joined: 17/08/09
sound like same problem as
sound like same problem as mine but i have 70 hp yammy , mine was a blocked jet. ran fine on the muffs under load would only get 8 knt
aaasnapper
Posts: 218
Date Joined: 15/01/10
Overheating
Is it overheating then going to limp mode?
Arthur Page will sort it either way.
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dakka
Posts: 275
Date Joined: 05/03/06
Yep problem was the coils on
Yep problem was the coils on my outboard cheers
"If we all fish for the future now there will be fish in the future"