Engine Stall at idle speed while in gear

M

msiroi01

New Member
May 21, 2012
28
LI Sound
Boat Info
260 Sundancer 2006 ~100 hrs
Engines
Merc 350
MerCruiser 350 on my '06 260 Sundancer. 52 mile round trip to Sag Harbor this w/e, then up to Hamburg Cove for a decent amount of boating. Purchased about 65 gallons of gas in all. While approaching the mooring at Hamburg Cove at idle speed, the engine stalled, and was a bit difficult to restart (had to use cold engine routine to pump the throttle to get started).

Coming back into dock at Pilots Point, engine stalled upon shift into reverse. Same restart issue. Made for a fun time watching the bow slowly approaching the rocks at the bulkhead. Thankfully some dock neighbors were there to grab our lines and prevent us from hitting them (and pull us back into the slip).

Thoughts? IOC valve? Water in fuel? Engine seems to idle ok, but doesn't like idle speed in gear, particularly reverse.

Thanks in advance.

Mark
 
Idle Air Control (IAC) valve would be my guess.
 
Thanks, JimG. Would there have been any alarms related to the IAC? I didn't hear any...

Also, after safely tied back up in my slip, I started the engine to see how it would idle and if it would stall in neutral. Ran it for 5 mins without a stall, but it idled at < 400 rpm. Basically around 380 rpm with some dips to 310 then back up. Never idled above 400. Still sound like IAC? Thanks again.
 
If you have Smart Craft System View, I believe the IAC malfunction would appear as an alarm.

You should be idling at about 600 RPM... yes, still sounds like IAC.
 
sorry to be so naive, but is it possible to have a faulty IAC with no alarm from smartcraft ( I do have smartcraft gauges). Boat is an hour away so I can't easily get back to check again for alarms/codes.
 
msiroi01 said:
sorry to be so naive, but is it possible to have a faulty IAC with no alarm from smartcraft ( I do have smartcraft gauges). Boat is an hour away so I can't easily get back to check again for alarms/codes.
Click to expand...

Sounds very IACish to me. I replaced mine twice in 3 years on the 350 Mag engine. You can get a generic from Auto Zone (or the like) for about 50-60 bucks so 1) its an easy swap to see if its the issue, and 2) if it isn't the issue you've just bought the part for you tool kit that you needed to have anyway.
 
Good point - reading other posts have me concerned about shift cable. The boat will idle, albeit at low rpm. It's the shift into reverse that caused the issue while docking.
 
Sous said:
Sounds very IACish to me. I replaced mine twice in 3 years on the 350 Mag engine. You can get a generic from Auto Zone (or the like) for about 50-60 bucks so 1) its an easy swap to see if its the issue, and 2) if it isn't the issue you've just bought the part for you tool kit that you needed to have anyway.
Click to expand...

Is there a part number for the generic $50-$60 IAC?
 
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