Backfire

[scoutonwater]

Okay, here's one of the issues that has reared it's ugly head during Saturdays trip to the lake.

It happened several times (10-12). The engine backfired sporatically. And not under any particular condition. All of them occured at speed (between 30-45 mph), and it would backfire, wait a while, backfire again, then nothing for several minutes, then out of the blue, another backfire, then nothing for a while, then a backfire...etc...etc...and occasionally felt as though it was losing a little power, not much. Almost like 200 lbs. were added to the boat instantaneously. Then resume speed again.

You could occasionally smell the fuel. Not consistently and not constant. My neighbor (more experience than me) thinks it's probably a carb adjustment. Not quite burning all the fuel.

Other neighbor (had lots of bad experiences) thinks that it has set over the years with no stabilizer and now the carb is full of varnish from not being properly treated between uses.

Who has the experience that matches this, and what was the verdict? Thanks in advance.

[3388sam]

Back fire through the carb or big loud bank out the exhaust lower unit.
Exhaust exits through the prop and it would be hard to hear.
Through the carb is timing issue.
Thought the exhaust - could be un-burnt/raw fuel. - This can cause some real issues if goes on - Blowing out bellows, flex fittings on the riser and manifolds

Was it for sure a backfire not just a stumble or miss? – Those can just be dirty or out of adjustment carb problems.

[seapuppy]

like ken says...can be fuel or carb problems...missing could be bad wires..distributor cap....fouled plugs....etc....be sure to check everything..when was the last time you had a complete tune up?..wires..distributor cap..plugs..check timing...do you have points??..check dwell??....is the carb tight??..I mean not loose on the manifold..mounting bolts....etc..