WOT only gets 2400rpm under load

[Searayjay]

Gentlemen,
2001 sundancer 240 5.0 efi throttle body, bravo 3 only 250 hrs.
New gas, ran great last weekend but noticed slight vibration on accel I think. This week, started fine, idled fine but under accel vibration and no power and would repeatedly only get 2200-2400 rpm. Idled back to dock seemed fairly smooth, in neutral revving seemed a little off but not obvious. Also noticed a couple times when coming back to idle, tach jumped quickly up while engine was nearly back at idle.
I plan to change fuel filter and plugs - rotor and wires are relatively fresh. Now since 2400 rpm max loaded seems electrical? Any ideas appreciated
Thanks
Dave

 

[kenny nunez]

Your engine may be going into "Gaurdian " mode . Also check that the impeller in the sea water pump is not damaged. I just went through that with my 6.2 .

 

[Searayjay]

Impeller is ok. 4 plugs looked great but 4 looked like they weren't firing. My understanding of Guardian mode is that it will also set off alarms but I had no alarns and good oil pres and temp was stable at 170.
This is frustrating. Also it has Bravo 3 so no shift interrupt I'm told.
Any help appreciated

 

[Bondo]

I plan to change fuel filter

Ayuh,..... Welcome Aboard,..... I'm guessin' I'm late with this comment, But,....

Inspectin' the Contents of the fuel filter was kinda an Important diagnostic tool,...

More often than not, a lack of good flow of clean fresh gasoline is the reason Wot power can't be made,....

Have ya run it since ya checked the spark plugs,..??
What exactly did the 4 plugs ya think weren't firin' look like,..??

 

[Searayjay]

Thanks all.
Good plugs were dry and grey, others were "wet" sort of.
Anyway ran it on flush muffs with new plugs fuel filter etc. And seemed to run great. Except I hear an odd noise when above idle-and revving it. It doesnt hesitate or stumble( revs strong) but i hear a clatter but more of a spinning clatter if that makes any sense. However, I never ran it on trailer- always in water so maybe noise is normal. Possibly just some spinning output shaft that isnt engaged when in neutral- I have no idea, but just thinking outloud.
Im going to try another run in river to see if it is any better.