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Mercury Tohatsu 25hp stalling idle

Steve A

New member
I have a 06 mercury 25 that I can't figure out. When I got it the grey fuel line made a mess of the fuel system. All line and tank are new. New filters. New injectors. Vapor separator is cleaned out. 45 psi of fuel. New idle air control valve. New intake air sensor. New water pump and thermostat.
The motor runs good cold and on top end. Once it has been running hard and you try to idle the motor surges up and down. Then it stalls. If you try to get it in gear it will also stall. Once you restart the motor you can get it into gear quick to move along.
I am really stumped on this one. I have seen these motors beat on by the rental company on our lake with no problems like this. My motor is like new with low hours.
I would appreciate anybody giving me some guidance that has had one do this.
 
I think I figured it out. Intake leak. Motor reacts when sprayed with starter fluid on center intake port. I ordered a new spacer and o-rings.
 
Update:
Items replaced
Intake spacer and o-rings
Both fuel filters
Cleaned complete fuel system with 46 psi to injectors
New injectors
IAC valve
Air temp sensor
Water pump and thermostat
Valves adjusted
Decarboned
New plugs

Motor still runs exactly the same. Runs good until it has been warmed up good. Will not idle stable. Idle surges and then stalls. The fuel pressure stays at 46 psi when this happens. Anybody have any ideas?
 
I know this is a few years old, but I have a 30hp doing the same thing. I am two years into trying to get this sorted out, and it's just driving me crazy. Mine doesn't matter if cold or hot though, it just has surging when returning from any higher throttle. I'm ready to junk the POS. This is what I experience. Sorry for the blurriness, I guess the phone was focused on the helm. https://youtu.be/ktK5MjTH8cs
 
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