15hp 2 stroke mariner starts well high rpm but no speed...help

awab

Recruit
Joined
Oct 20, 2011
Messages
4
dear reader
bought a 15hp mariner with no spark. cheap.
installed a new coil and had spark. been very proud. now in the water it starts perfect but I get no speed. the engine sounds fine. have high rpm but I am no going faster then with a 2hp. The pro is fine. no spin. been reading could be the fuel diagram there is there is a high speed and low speed thingin the electric.
perhaps you guys have more knowlege.
thanks
peter
 

Sunfish12

Petty Officer 1st Class
Joined
Feb 6, 2011
Messages
260
Re: 15hp 2 stroke mariner starts well high rpm but no speed...help

If you have high rpm then there shouldn't be a problem with the fuel. In reverse will it go pretty fast? It may be a lower unit problem.
 

awab

Recruit
Joined
Oct 20, 2011
Messages
4
Re: 15hp 2 stroke mariner starts well high rpm but no speed...help

hello
thanks for the responce.
I does not sound like the lower unit. There is no strange noise. The engine goes on high rpm but the is no real push forward. The prop is not spinning. I controlled this. It feels like something is holding the dinghy. The rpm has no high pitch sound like normal. Its more like the power is not arriving the water. had a mechanic here and he sayed something about cleaning the carburator. but he did something on another boat was quite buissy and had not really time for me. sorry for my bad english. Its not my motherlanguage.
peter
 

Mi duckdown

Commander
Joined
Apr 14, 2007
Messages
2,575
Re: 15hp 2 stroke mariner starts well high rpm but no speed...help

SERIAL NUMBER, first. and the compression IS?
 

Sunfish12

Petty Officer 1st Class
Joined
Feb 6, 2011
Messages
260
Re: 15hp 2 stroke mariner starts well high rpm but no speed...help

If theprop is not spinning then your not forward, the drive shaft spline is stripped in the engine, something is wrong with the lower unit or the prop is slipping.
 

Mi duckdown

Commander
Joined
Apr 14, 2007
Messages
2,575
Re: 15hp 2 stroke mariner starts well high rpm but no speed...help

Sunfish it could be as simple as linkage.
untill awb posts. who knows.
 

awab

Recruit
Joined
Oct 20, 2011
Messages
4
Re: 15hp 2 stroke mariner starts well high rpm but no speed...help

sorry cannot post the serial in the moment.
I am not on the boat and need some time to get there.
its not a linkage or compression problem.
thanks
 

Martin7777

Recruit
Joined
Nov 2, 2011
Messages
1
Re: 15hp 2 stroke mariner starts well high rpm but no speed...help

Hi, this may not be relevant in your case, but a friend of mine had the same symptoms. It took three years, but he eventually discovered that the cause was simply that the wrong propeller had been fitted by a previous owner. The blades were about an inch smaller than the standard prop. High revs but no real speed.
Might be worth checking, hope this is helpful, being my first post in any forum ever.
His engine is also a 15hp 2 stroke Mariner.
 
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