Outboard motor question

Question

My engine conks out when Im docking the boat. Neutral is ok but when in gear and going a the slowest speed when docking ,it quits. Its a 1999 150hp mercury engine

Answer 1

You should be able to idle this engine all day without missing a beat.  I have a 135hp Merc on my fishing boat that I use to troll for 6 to 10 hours on an average fishing trip on Lake Ontario and it never stalls.  Check your rpm at dead idle, it should be around 800 in gear like mine.  If it's lower than that, adjust the throttle linkage to boost it up.  If you still have a problem, I would recommend having a qualified mechanic check it out.

Answer 2

Agree with both of the above -- it should idle all day, or else it needs attention.  But most don't because they never get the attention they need.  ;)

Carb or EFI?

You sure the idle adjustment is the throttle?  I'd of bet the idle was adjusted with spark advance alone, and the throttles stay closed.

Any case, if the idle speed is correct, and leaning out the slow speed mixtures don't help, the most likely scenario is worn out and/or sticking carb floats letting just enough fuel past at slow speeds to flood it out.

Answer 3

The idle in gear speed might be a little low, or the carb adjustments might be to lean.  Most outboards don't idle well for long periods so 2-3 min. it'll start to run rough.