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Brian Whatcott Brian Whatcott is offline
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First recorded activity by BoatBanter: Jul 2006
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Default Help needed on a 40HP Mercury Outboard (S/N 5991890)

On 4 Oct 2006 17:28:30 -0700, "kmatus" wrote:

We bought our first small boat for lake fishing a week ago. It is a
used 14' jon boat circa 1981 (according to the license). It had on it
a 40 HP MERCURY engine with serial number 5991890.
/// I took it on faith that it was a 4 cycle and we put premium gas
into the fuel tank with no oil added.

///
Figured out at that point it was a two-cycle, so I added the
pre-requisite 50:1 ratio of two cycle engine oil (by the way, I just
used generic two-cycle engine oil, is there any difference between that
and marine two cycle oil?).

I also changed the spark plugs and the little in-line fuel filter.
The top spark plug was charred.
/// Does it still sound like I have a fuel problem?

I'd appreciate any helpful suggestions.


Go buy a compression gage, and an inline spark tester.

See if you can get more than 80 psi out of the cylinders,
and a decent blue spark at each plug.

If yes to both, you have a fuel problem

Brian Whatcott Altus OK