for what its worth , my 40 hp merc. o/b was purchased 4 years ago and my mechanic told me to run only lower octane reagular gas , i never did ask why , now i know .
for what its worth , my 40 hp merc. o/b was purchased 4 years ago and my mechanic told me to run only lower octane reagular gas , i never did ask why , now i know .
okay, down to 89 only then but if there's anybody out there that know's the mechanics as to why and would it really make you lose power please explain. Thanks.Originally Posted by diamondbear
I was having similar problems with my 15hp Evanrude. I took it in for service and they ended up replacing "the power head". It is a electrical component that operates "one" of the cylinders in my 2 stroke. Part was $118.00, labor was about $150.00 (three screws and a din connection) :(
miguel
Lizzay, this is only my opinion, and I don't want to get into a big dissertation on the internal combustion engine.So here we go, the fuel we are burning in the outboards is supposed to "match" the performance of how the engine is setup, therefore with premium grade gasoline with the higher octane rating, burns slower or harder to ignite and with the lower compression and retarded ignition timing we have in our motors, it struggles to get a complete burn,on the other hand when the components "match" the fuel requirements, such as higher compression,advanced ignition timing and a high revving engine, the efficiency of the combustion process(burn) is complete, there is also a down side to too much compression and thats detonation, but thats another story.
So regular gas is easier to burn(burns faster) in our outboards, keeps the heat in the chamber for a complete combustion process.
hope this sheds some light on the subject.. Kelly k
One thing I haven't looked at is hotter spark plugs since its hard to keep the heat in the chamber because of the cold water cooling...... hmmmmm.........
Sorry I didn't answer this first, I will try to remember why they would not put this under warranty, I think since this was an exploratory check up it was not covered under warranty, I think they charged me $80 to tell me the carb needs rebuilding........ Kelly k
k so i siphoned all the gas out of the tank tonight.. and will fill will 87 tomorrow.. just half the tank and see how it goes.. will be at the Pudd if anyone is going to be out there...
i will update if it runs any better.
If I may suggest, You might want to run the engine with the water hooked up so that any premium gas thats left in the system is burned off, I run my motor on the stand before I go out, just to make sure everythings ok, it also makes it easier to start in the morning.
Kelly k
you know you could put that old gas in your car dont you?
Good luck!
ok.. so i siphoned the old gas out to another tank (temporary), filled up with some 87 octane.... still having same problem..
full throttle.. .power is still very weak...
although the shaking has seemed to have gone down from before...
i will be checking spark plugs and maybe even take a look at the carb later tonight..
i talked to Brian at Johnson Marine in Ontario.. and will be bringing it to them next week for an annual tune up and have them check the problem...
Hence the reason why higher reving/faster cars states us to use high octane fuel because it needs that much to match up with the performance of the engines. Very well done. Thanks for all that info.
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