Worn spark plugs are the most common cause of misfire fault alarms, but there are many other things that can also cause them.  The SPN 65591 FMI 7 fault can cause engine power reduction, but will not cause the engine to shut off or stall.  Loose or corroded electrical connections can cause low voltage in several of the engine and boat circuits, which can cause intermittent or aberrant running issues and alarms.

1 hour ago, Parkerbw85 said:

@Sparky450 Thanks !

Hopefully it worked for you! 

Late to the party - mine started missing Saturday under full load surfing then was fineunloaded on trio home.  Today we made it 1/4 mile out as ND itshut itself down.  Missed the rest of the way back and nopower.  Pulled plugs and replaced them and it ran much better, but not perfect.  Still getting the "service required" message and vibration/miss under load.

Looking for sources for O2 sensors and ignition components.  The 350SS looks to be basically a 5.7L vortec engine from 96-98 with a different intake.  I plan to replace the sensors, cap, rotor at a minimum

In unrelated news, I hate that my boat has cats...

On 6/3/2024 at 4:54 PM, HollywoodBall said:

Care to add anything here? I've seen this and thought about it.  Looks pretty cool and handy, but was curious about real world reviews.

We dig it. My only advice is that getting your trailer submerged just right helps a lot. You don't want to have to power the boat up very much, or at all if possible. I have the wife pull onto the trailer and have the bunksstoo the boat about a foot short (ideally) and then she keeps it in gear as I gently back the truck up until it latches. If you then pull out slowly the boat seems to center itself as it settle on the bunks. Works for us on our local ramp. It also give you the ability to just use the winch strap like normal if you feel like it for some reason. Has been a good investment IMO.

Tried a few times and nothing was in there. Tonight it finally shut itself down going full power to our surf spot.  Limp mode?  Obvious vibration/misfire.  

Coding:

SPN:65591  FM1:7

MECHANICAL SYSTEM NOT RESPONDING PROPERLY

Changed the plugs and runs better now but still giving the "Service required" warning, but no code the last time I chexked. After my post op test drive to 45mph/5300RPM.