Mercury 90hp 4 Stroke stalling problem

[ChrisSupple]

I have a 24’ pontoon with a Mercury 90hp 4 stroke outboard. My engine info tag says that I have a 2007 90ELPT 4S. I’m working on it for a family member. My problem is that while in gear(F & R) @ idle, when I shift into Neutral, the engine stalls every time. It will immediately start with the ignition key while in Neutral. Otherwise, this engine runs/accelerates very well. I replaced both fuel filters, engine oil & filter, Lower unit gear lube, impeller, spark plugs, & drained/filled fuel tank with non-ethanol 30 gallons. This problem makes docking very inconvenient. Any ideas on what is causing this issue? Thanks

 

[PeterInSa]

To me your idle speed (RPM) in Neutral is to low, this can be adjusted with the control rod inside the motor cover.
However wait for a more experienced Merc user to comment.

 

[ChrisSupple]

Thanks for your reply. I haven’t checked the idle rpm with a gauge, but it doesn’t seem to be low at all. I’ve read several posts on different forums & it appears that the neutral safety switch isn’t working properly. Supposedly, it makes the engine stumble for a split second when shifting back to neutral, allowing the drive clutches to relax enough to remove the drive load, allowing for an easy shift to neutral. This is a plunger style switch under the motor in the bottom of the upper cowling. I’ve had several boats over the past 30 years, but they’ve all been inboard/outboards. This is my first experience working on an outboard. Any thoughts or suggestions are much appreciated!