MaltaBoating
New member
Hi everyone. I have a 90hp Mariner 3 cylinder, 2 stroke, 2004. It was garaged for several years and after I acquired it and its boat, I was delighted by its condition. After months detailing and repairing the boat and running over the basics on the engine I put the boat in the water.
The engine bogs but it’s erratic. Sometimes it runs like a dream, gets beyond 30 knots and all seems perfect, it can even pull a water skier or a tube. At other times the power goes up and down like a yo-yo with a mind of its own. Often it won’t even get up on plane, or just cuts out. It is very erratic.
Out of the water, without any load, everything works, performance is faultless. I have eliminated fuel, fuel lines, tank, fuel filters (by using an external, brand new tank with new lines and filters), compression is 125 psi per cylinder, every fluid in the engine has been changed so it is fresh, and I have had an engineer check it over. Still no joy and it is driving me to the point of insanity.
Having scoured the internet, I believe I have narrowed down the possible issues to:
The engine bogs but it’s erratic. Sometimes it runs like a dream, gets beyond 30 knots and all seems perfect, it can even pull a water skier or a tube. At other times the power goes up and down like a yo-yo with a mind of its own. Often it won’t even get up on plane, or just cuts out. It is very erratic.
Out of the water, without any load, everything works, performance is faultless. I have eliminated fuel, fuel lines, tank, fuel filters (by using an external, brand new tank with new lines and filters), compression is 125 psi per cylinder, every fluid in the engine has been changed so it is fresh, and I have had an engineer check it over. Still no joy and it is driving me to the point of insanity.
Having scoured the internet, I believe I have narrowed down the possible issues to:
- Ignition stator failure on high side.
- Idle mixture/low speed mixture badly adjusted.
- Dirty jets or carburetors.
- Fuel pump or gaskets in fuel pump not working.
- Coils/CDM have issues.
- Reed valves are problematic.
- Electrical temp sensor failure.