88 Johnson bogging down

[MIScott]

Originally Posted by MIScott

So I've got an Evinrude 140 (87) that sounds like it's doing somewhat the same thing. Already replaced the fuel filter (which definitely helped start-up), and brand new properly gapped plugs (look great after running, not fouled)

Engine runs great under 2200 rpm trolling along, and occasionally it will let me really open it up (was running 33 knots yesterday), but as soon as I pull back throttle (from fast running) the engine will drop down to 2200-2500 rpm and not let me get back up in engine speed. I can NEVER just get on the throttle and get up to speed. (Which I'd like to do because my kids are DYING to go tubing.)

I'm "up north" and not at home so I don't have my usual set of tools, diagnostics, etc. Any EASY tests I can run to see if I can pinpoint the problem?

Finally figured this sucker out.....after replacing ALL the fuel lines, fuel filter, primer bulb AND rebuilding the carbs....still had the issue.

Then I saw a post talking about the temp sensor wires (tan) being routed near or over spark-plug wires possibly causing a false signal. Opened the cover and sure enough, one of them was laying directly across one of the plug wires. I zip-tied the sender wire up out of the way and took her out for a sea-trial last night.

Boat ran flawlessly for the entire time I was out. Fired up immediately, ran great at all speeds, no bogging/hesitation.

Basically the false signal was making the engine think it was overheating putting it into limp mode and preventing engine speeds higher than ~2200 rpm.

SO HAPPY!