Guardian Mode?

kordo

Last week, my 6.2 engines would not go over 4150 rpm.  Prior to that (this season), no problem getting to 5000 rpm.  No alarms or hesitation, everything seems fine, just can't get over 4150 rpm.  Any ideas?  I've changed the fuel filters (cool fuel module), put in new gas (gas was from last year and below 1/4 tank) and cleaned the flame arrestors.  Will try again this weekend.  Thanks.

Liberty44140

When did you last do plugs, cap and rotor?

kordo

Haven't done them since I bought the boat in 2017.  Would plugs, cap and rotor account for a change from one week to the next with no change in idle, starting, performance up to 4150 rpm or lack of alarms?  Thanks.

YYZRC

Both were limited to 4150?  I would agree with @Liberty44140 on bad plug or wire or cap/rotor but both engines limited at the same time to the same RPM is strange.

kordo

Yes, both, but I have the digital controls which synchronizes the engines.  Good point, I'll turn synch off and try them individually to see if they go over 4150 rpm.

YYZRC

One of my 6.2s had a bad plug which limited it to around 4000. Probably something simple like that. 

TonyG13

If you have DTS also make sure you are not in "Dock" mode. I did that last weekend and couldn't figure out why I was at full throttle and not going anywhere.

Liberty44140

If your plugs are 2017 then they may be ok but if they are easy to replace them replace them. Cap and rotor are super easy to replace and even though they last years just a little moisture and the rotor will fail. We just did a trip with someone whose rotor failed after only one season. Could have been a bad part but we had just ran 3 hours in the rain and his boat had no canvas up. 

LaRea

Digital sync only works when the RPMs are somewhat close.  It won't try to sync if one engine is at 4150 and the other at 5000.  

Aqua_Aura

There was a member on here that was only 1 year on cap and rotor but they were corroded and replacing them solved the issue. 

kordo

Figured it out.  Fouled bottom, lots of small zebra mussels.  I have used bottom wax since 2018 with no problems but it looks like this year the zebra mussels finally got me.  I am on Georgian Bay and the zebras have been around for years but this year they must be worse.  I'll poke around at trawler speeds until the end of Sept and then get the bottom done.  I've heard that some people around here just sand the gelcoat and then apply bottom paint.  I have also heard you need a barrier coat before applying the bottom paint.  Any recommendations for fresh water Georgian Bay?  Thanks. 

YYZRC

Wow that’s crazy @kordo ! I thought the zebras liked areas where there is water flow (intake pipes etc). Maybe you aren’t using the boat enough?!

Aqua_Aura

Barrier coat isn't an absolute need on the newer boat resins but if your gonna do bottom paint it definitely wouldn't hurt. 

LaRea

It's hard to recommend a paint ... you'd be better off talking to boaters in your marina to see what works. 

CSC Micron Biolux used to be the gold standard around here, but lately it doesn't work as well as it used to.  It's one of the most expensive paints, and I used to get 3-4 seasons from two coats.  Lately, it will barely last two seasons.  

My other advice:  for ablative paint, two coats will last twice as long as one coat.  The paint wears away like a bar of soap.  You want a thick coating.