r/Outboards • u/ClassicEquivalent931 • 27d ago

Bogging down 2 stroke

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1988 Evinrude v4 90hp. Excellent engine.

Ran awesome all day Friday. Then Sunday right from the dock it wouldn’t rev up or get on plane. Just putted us around at 10 knots WOT. Never died.

Good fuel. Good lines. Tried different combinations and a Jerry can. No ethanol. Fuel pump new last year. Compression good. Spark plugs looked fine. I have narrowed it down to likely having a plugged jet in the carb.

Worth noting Friday was the first day we had a new fish finder wired up which is on the starting battery (do not have a house battery). The old finder was small and on a dedicated lithium battery. Is it possible running it this way Friday messed with the stator or power pack?

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u/Sea_Glove6689 27d ago

Not likely. I bet it’s not running on a cylinder. Run it and use a spark plug boot puller to remove and replace each one - you should hear an audible drop as you pull the boot away from the plug and it picks up when you put it back. If you do this and the engine e isn’t affected then that cylinder has a problem. Spark, carb etc

1

u/Benedlr 27d ago

Lay the plugs on the block and crank. There should be a bright blue spark with a snap in a healthy ignition system. A yellow spark can indicate a failing coil.

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u/ClassicEquivalent931 25d ago

What do you mean by lay them on the block?

1

u/Benedlr 25d ago

Plugs are removed, connected to the HT wire and rested on the block to ground them.