2008 Searay Amberjack lack of engine power

[Rocky5514]

Hope someone can shed some light for me. Recently purchased a 2008 Searay Amberjack 290 with Twin 260HP 5.0MPI...….prior to any work being done to the boat it would get about 37-40MPH on WOT with 4-guys and 1/2 a tank of fuel...& some gear. I had a full tune-up done on both engines recently, cap,rotor,plugs,wires,thermostat,impellers,oil,gear oil,pulleys,fuel filters, etc. manifold and risers under two years replaced.
I took the boat out yesterday and the engines would not give me sufficient power to plane. Maximum reading was 2900 RPM on both engines going no faster than 10MPH. I was on the intercoastal smooth water. Granted I had 12 people.....8 adults, 4-kids, total weight was about
1800lbs with another 200lbs of food, etc with 1/2 tank of fuel. I was heavy but even with my trim down, trim tabs down, and weight pushed forward to bow it would not power over 2900 rpms. Funny thing is on the way back home I was able to get it to plane better and I was able to get to about 28-30mph at around 4000rpms....better but seemed sluggish.
Mechanic checked the boat and said I need to replace my block pressure sensors.
So after a long winded thread my questions are the following.
1. If weight was my primary factor then why did I get more than double the speed and better engine power from earlier in the day with the same amount of weight?...….did current play a role?
2. Can those bad sensors cause the motors to reduce power?
3. I made sure my Dock mode was off on my STS shifters.... is it possible the system thought I was still in dock mode, thus not allowing the motors to accelerate more?

Any help would be greatly appreciated.

Luis

 

[Rocky5514]

Typo error on my above post......Mercury Smartcraft DTS shifter not STS

 

[Lazy Daze]

??? Your signature says 'v-drives', but you mentioned putting your trim down, which would indicate outdrives... Assuming outdrives, which model?

Had the boat been sitting for a while in the water before being used? ANY growth (even just a thin layer of slime) will affect performance - even more noticeable with a full load. Using the boat could have worn off some of the slime.

 

[scoflaw]

Sure wind and current can do that

Did he make his judgement from a laptop diagnosis ? That 555 pcm can reduce power to 90%. Was he seeing that ?

 

[fwebster]

I think your expectations are way too high for a 290AJ w/350's.

I have limited experience with 290AJ's but have a good friend that had one. He bought the boat as a dual purpose cruiser for his wife and fishing boat for him. I have run it or been on it hundreds of hours since I don't fish my boat. It had twin 350's with B-III's. The boat wouldn't plane with 3 adults, full water, ice, fishing gear and full fuel onboard. I never saw it leave the dock with more than 1/2 fuel because of the performance.

This isn't my first rodeo and we tried everything we knew to do to improve things short of repowering with bigger displacement and longer stroke engines. He kept the boat about 2 years and eventually sold it and bought a center console powered by twin Honda 250hp ob's.

Power problem solved.......and he says his wife can learn to like the CC or stay home.

 

[JimG]

and is it 5.0's or 350's?

 

[fwebster]

The boat I am referring to had 350 cu in, 5.7L gm engines rated at 260hp and was a 2001

 

[JimG]

The boat I am referring to had 350 cu in, 5.7L gm engines rated at 260hp and was a 2001

Sorry Frank... my question was to the OP... his story and his profile don't match.

 

[Stee6043]

Before spending a dime on parts/service I'd take it out again with 3 or 4 people and see if it runs correctly.

12 people is a lot....

 

[Rocky5514]

Thanks for all your replies...….my engine config is wrong on my profile. Need to change it. Yes it is Merc's stern drives Twin 260HP 5.0MPI with Bravo lll's
With four adults and gear I was able to plane in about 8-seconds.....with the load I had this weekend it did not plane most of the day but for some odd reason it planed and went faster when I was heading home......same water conditions as the day but a bit less wind.
Scoflaw what is a PCM 555 error code. My mechanic did show a faulty block pressure sensor and a sticking starboard side thermostat. The thermostat was brand new....possibly defective?

 

[Lazy Daze]

If you had a fault that put you into partial limp mode, though, there should have been an audible alarm along with a message on your Smartcraft.

Small clarification here, but in case you are googling... you have an ECM 555 engine computer, not a "PCM" 555. The PCM is used with the 496. Same idea in the end, though.

 

[scoflaw]

Let the guy do his job, sounds like he has a handle on it. 1 bad sensor can give a false fail on another one.

 

[Rocky5514]

Yes I did show an error fault on my smart gauge but no audible alarm.....unless I just did not hear it with all the noise.
Heres some pics of the boat and helm.

 

[Lazy Daze]

Yes I did show an error fault on my smart gauge but no audible alarm.....unless I just did not hear it with all the noise.

Out of all of the information you originally posted, THAT was the one thing you didn't? It would have been good to lead with that!

As Scoff mentioned, it sounds like your mechanic has it under control. You can try swapping sensors, if you want to.

 

[Rocky5514]

That’s true my bad.....I forgot to mention that, only when you mentioned the gauges on your prior post, did I recall that at some point the fault code did show on the starboard gauge. Thanks for the help we’ll see if the mechanic gets it all worked out!

 

[mwph]

Disclaimer.....I can not help the OP with any supposed mechanical or electrical he may or may not have. I can however, even with my limited knowledge, offer the absolute BEST piece of advice in this thread.....

Never again put 12 people on a 29' boat. Even if they are the 12 lightest people anyone can imagine.

AND with all due respect to the seasoned members of this group....I don't care how safe you say it is, how many people you've had on your boat or how well behaved or experienced those 12 people were. They were in a position that was not in any way a good idea.

 

[Lazy Daze]

That’s true my bad.....I forgot to mention that, only when you mentioned the gauges on your prior post, did I recall that at some point the fault code did show on the starboard gauge. Thanks for the help we’ll see if the mechanic gets it all worked out!

Good luck - hopefully it's a quick fix.

 

[b_arrington]

Never again put 12 people on a 29' boat. Even if they are the 12 lightest people anyone can imagine.

I have to agree that 12 people on a 290 AJ is too many. Both for safety and performance. My first thought was an overweight problem.

 

[Brite Idea]

I like the boat but with the base engine packages it is under powered. I agree 12 people is both a safety concern and too high of an expectation for that boat. I spent time on a friends 2004 290 AJ with those engines and with 4 guys and gear going fishing it struggled to get on plane. After your mechanic resolves the error issues determine if the boat with a normal load will achieve WOT. The boat is most likely over propped. The Bravo III's are good but with minimal power too much prop is like dragging an anchor while trying to get on plane.

 

[Rocky5514]

Finally took the boat back out after getting the block pressure sensor repaired and with 10 people it reached 33MPH WOT and planed in 15seconds......long but planed. With 4 guys and some gear it planes around 10-12 seconds...….
One thing I did notice the Trim tabs were not working.....will replace this weekend and see if I have improved performance. Thanks for all the feedback