2004 FV 342 performance issue

mikejudd65

throwing this out there .... 2004 FV 342 , 5.7L Horizons , bravo 3 ... very reputable Merc mechanics have looked at it found nothing, no alarms, no guardian mode .... symptom; with load or without (people) , cannot get above 3000 rpm on both motors, mechanic found bad water pressure sensor, replaced but still have problem,  heres the kicker, seems intermittent , ran last weekend 28'ish knots all the way home, today had the problem, ran tug boat speed all day .... any ideas? anyone?

Black_Diamond

Will the engines get above 3k when not in gear?

mikejudd65

I'll confirm today but since its sporadic issue I assumed they would and I presume the mechanics would've done that

aero3113

Sounds like it could be water in your fuel, try putting in new fuel filters.

mikejudd65

new fuel filters put in beginning of season, I'll need to check the inline filters for when they were last replaced 

Stodge

Just because the fuel/water separators were new at the beginning of the season does not mean that they don't have water in them now.  But I'd expect the engines to just quit if there was water in the fuel.

mikejudd65

thanks Stodge, true and I agree, the boat is new to us this year. At spring commissioning earlier this year when the fuel/water separators were replaced the old fuel I poured out of the old filters was very very old as indicated by the color of the gas, orangish/brownish in color. I've filled up several times this year but you're right , could be filter change time again. I'll do both again as well as the inline and see how she runs. We have a trip scheduled for the upcoming weekend. 

Stodge

I mention that because I had an issue this season where the O ring for one of my fuel caps fell apart and was missing allowing rain water to find it's way into the gas tank.  They ended up removing 2 gallons of water from my starboard tank.  

Just tossing it out there.  Hope you figure it out.  Sounds like something any of us could encounter and would be good to know cause/cure.

mikejudd65

UPDATE Sept 1st 2018: 
all is fixed according to mechanics.
- seperate issues on each engine.
- stbd engine started stalling on them on sea trialing/testing. replaced distributor and coil. 
- port engine: they found y-pipe flapper gone,  they scoped the engine couldnt find pieces of flapper , they concluded its stuck in outdrive somewhere. exhaust blockage. They bypassed exhaust bellows to exit outside of drive. 

--- achieved 36kts at 4200rpm
--- they advised that due to age of boat,  2004 , 10% hp reduction due to ethanol and orginal 24p props,  next year go to 22p props, will put motors in sweet spot 

more to come after labor day weekend,  we have an overnight trip scheduled


 

Handymans342

You should be at 47 mph at 5000 rpm

pistole

mikejudd65 said:

UPDATE Sept 1st 2018: 
all is fixed according to mechanics.
- seperate issues on each engine.
- stbd engine started stalling on them on sea trialing/testing. replaced distributor and coil. 
- port engine: they found y-pipe flapper gone,  they scoped the engine couldnt find pieces of flapper , they concluded its stuck in outdrive somewhere. exhaust blockage. They bypassed exhaust bellows to exit outside of drive. 

--- achieved 36kts at 4200rpm
--- they advised that due to age of boat,  2004 , 10% hp reduction due to ethanol and orginal 24p props,  next year go to 22p props, will put motors in sweet spot 

more to come after labor day weekend,  we have an overnight trip scheduled


 

36 knots is alot

Black_Diamond

47 mph?  Not in my 342. 

Handymans342

Raybo 47 all day long

Liberty44140

With 22p props wot on my 342 is 40-41 mph at about 5000 rpm. That said I believe guys with 24p have reported higher wot with 24p. 

zaverin1

Higher pitch would lower your rpm but give you faster wot 
dropping a pitch will raise your rpm and sometime keep it drop wot