I have a 2010 SD260 with 350 mag...

[MDM1]

I have a 2010 SD260 with 350 mag engine. Had a full load of 11 people & gear this past weekend. Running at about 25-30 mph the engine throttled down and the smart craft gauge reported engine guardian system activated. I pulled the throttle back to neutral and the alarm clears. I run it back up to about 25 mph and shortly after the same thing happens. I was able to get back to the dock running at about 10-15 mph with no alarms and no other problems. Any suggestions?

[wingless]

This page shows Smartcraft Guardian faults and causes.

https://www.perfprotech.com/blog/marine-outboard-motors/mercury-marine-smartcraft-and-guardian-system-warning-horn-alarms

Was the tone continuous? Likely caused by a cooling issue.

Verify proper cooling flow and examine for internal corrosion.

[doug5]

I would recommend getting it to a service center. One possibility is that the water pump is failing at higher speeds.

[MDM1]

Thanks for the info. I hope to take a look at it this weekend and I will post any results that I find.

[MDM1]

UPDATE: dumped 4-cans of Seafoam in to the tank (65 gallon) nad filled it up from the prior week (about 31 gallons of gas) from a different gas station that we previously filled. Had "0" problems all day with a crew of 9 plus gear! It appears that we got a hold of some bad gas! The proof- my wife filled her car tank on Friday and shortly after the check engine light came on. Autozone diagnosed it as a fuel pressure sensor. Not thinking, we filled up the boat on Saturday and had problems later that day. we put some gas treatment into my wife's car the following week with the next fill-up (at a different gas station and the check engine light cleared as well. Both problems fixed! I notifoed the Kroger station where we filled up, but they said they ahd no other complaints (imagine that).

[MDM1]

sorry for the mis-spellings...typing too fast

[wildog]

My friend these Adam is that you put in your gas tank and not good stuff when they mix with big ass it becomes like sludge jelly . I put in Lucas fuel injection additive you can get that at Walmart or AutoZone . Another additive are use Marvel mystery oil in the gas tank cleans everything from the engine fuel system out . You’ll see the difference in performance

[Jackster]

Had the same problem with the starboard 350 MAG on my 2012 SDA 330. Check the alarm history. If you have VesselView, look at the alarm detail. In my case the alarm was due to "low pressure." The alarm didn't indicate which fluid was low pressure, but I saw the cooling water pressure was much lower on the starboard engine. Turned out to be the pressure sensor. I hear they fail frequently.

[Big_mike1]

Have someone check codes to many things could be wrong