Reply
 
Thread Tools Search this Thread Display Modes
 
Old 06-14-2009, 03:45 PM   #1
Ensign
 
Join Date: Aug 2008
Location: Southern Maryland
Posts: 8
Default Only getting 4200 rpm @ wot???

Hi again all

I am hopeing to get an idea of what is wrong with My in laws Vessel. the Vessel is a maxum scr-2900 with a 5.7 liter eng and a Bravo 3 outdrive.

The Problem is We are only getting a maximum 4200 rpm @ wot, I dont know what happened just a few dyas ago we were grabbing at least 5500 rpm.

I have yet to look at the Rotor and cap and the ignition system, Was hopeing to do that later to day. I know we are geting wot as i have looked to the throttle body and butterfly valve is pegged open. So mechanically its at wot.

Could it possible need a tune up or maybe i need to dropped under the boat and check the out drive for fowling????

Any ideas would be appreciated as i have had AWSOME support from the forums here, Keep up the good stuff

Chris
__________________

Maxumhiredhelp is offline   Reply With Quote
Old 06-14-2009, 11:51 PM   #2
Admiral

 
seapuppy's Avatar
 
Join Date: Nov 2005
Location: Everett Wa
Posts: 4,681
Default Re: Only getting 4200 rpm @ wot???

yes.....start with the bottom...if it's crapped up with a mess of growth....then no matter what your doing will get it too WOT...

if that doesn't help..then start with a tune up...does it have points or solid state ignition???..probably the SS ign....if that's the case...then when was the last time you replaced plugs..distr cap...rotor....and wires??...

how bout the gas...is that ok???...I mean fairly fresh??...filters...when was the last time you replaced the fuel filters.????...if the engine is carbed ..could be a problem with the carb or the filters....by the suggestion that you were getting 5500rpm..I'd say it was MPI...which I would suggest that you clean the intake screen ...

SP irate:
__________________

__________________
Don't compare your life to others. You have no idea what their journey is all about.
------------------------
SSN683 Association member
Par Excellence
------------------------------
2008 Bayliner 340 - "Wild Whim"
--------------------------------------
I live in my own little world....but it's okay-they know me here!!!

Avid practitioner of the martial art: KLIK-PAO.
Tap-Rack-Bang

Anyone that sez "Size doesn't matter" has never owned a boat!
seapuppy is offline   Reply With Quote
Old 06-15-2009, 03:33 AM   #3
Ensign
 
Join Date: Aug 2008
Location: Southern Maryland
Posts: 8
Default Re: Only getting 4200 rpm @ wot???

It should not be growth or something along those lines it was hauled and cleaned this winter and only been in the water about a month. But i will be sure to take a look. The father In law may have picked somthing up here in the Solomons island area of maryland.

Will take a better look at the screen it seemed to be pulling air fine while i was checkng things while under way it appeared to be pulling good air. BUt I will look.

Yes its a Solid state ignition, I will take a good look at all filters and ingnition items as we have mentioned.

Hope We fine it soon.

Thanks a million again

Chris
Maxumhiredhelp is offline   Reply With Quote
Old 06-15-2009, 05:46 PM   #4
Lt. JG
 
Join Date: May 2009
Posts: 22
Default Re: Only getting 4200 rpm @ wot???

Man thats crab pot haven down there. Yeah check for a line or something around the prop or shaft.

I had something very similar a couple of years ago. I picked up someones underwear and the whole nasty thing got pulled down in behind the prop around the thrust plate. You might need to remove the prop to check for sure.

Good luck!
__________________
Charles W. Spangler, Captain, USCG Master
Home Port: Chesapeake Bay, Middle River, MD.
yorkcoparamedic is offline   Reply With Quote
Old 06-21-2009, 02:07 PM   #5
Ensign
 
Join Date: Aug 2008
Location: Southern Maryland
Posts: 8
Default Re: Only getting 4200 rpm @ wot???

Well here is an up date,


Changed everything in the ignition system, except plugs and plug wire.

Well we gained a few hundred RPM's, But still lacking quiet a bit like around 500 or so. So I guess its time to go into the water and take a look.

If anyone else can think of a few things i missed let me now for now It's time to get wet

Cheers All

Chris
Maxumhiredhelp is offline   Reply With Quote
Old 08-27-2009, 03:22 PM   #6
Ensign
 
Join Date: May 2009
Location: Pax River, MD
Posts: 4
Default Re: Only getting 4200 rpm @ wot???

Don't know if you figured this out yet, but I work down on base (Pax River) and I know a BM2 who maintains the mercruisers on their port boats. He does lots of work on the side and I usually pay him in beer. Can't beat that!
Big Joe is offline   Reply With Quote
Old 08-27-2009, 03:59 PM   #7
Admiral

 
ss3964spd's Avatar
 
Join Date: Jul 2009
Location: Fairfax Va
Posts: 1,512
Send a message via Yahoo to ss3964spd
Default Re: Only getting 4200 rpm @ wot???

Are you certain the 350 Mag is even supposed to spin to 5500 at WOT?

Seems excessive......

Dan
ss3964spd is offline   Reply With Quote
Old 08-27-2009, 10:27 PM   #8
Admiral

 
seapuppy's Avatar
 
Join Date: Nov 2005
Location: Everett Wa
Posts: 4,681
Default Re: Only getting 4200 rpm @ wot???

if it's an mpi engine..it will spin right up to redline...or the rev limiter..whichever is first...
if it's carbed..then you should be between 4200-4800 rpm..
as for the 500 falling short....that could be tach error...or growth on the hull..


SP irate:
__________________
Don't compare your life to others. You have no idea what their journey is all about.
------------------------
SSN683 Association member
Par Excellence
------------------------------
2008 Bayliner 340 - "Wild Whim"
--------------------------------------
I live in my own little world....but it's okay-they know me here!!!

Avid practitioner of the martial art: KLIK-PAO.
Tap-Rack-Bang

Anyone that sez "Size doesn't matter" has never owned a boat!
seapuppy is offline   Reply With Quote
Old 08-28-2009, 02:20 PM   #9
Admiral

 
ss3964spd's Avatar
 
Join Date: Jul 2009
Location: Fairfax Va
Posts: 1,512
Send a message via Yahoo to ss3964spd
Default Re: Only getting 4200 rpm @ wot???

Quote:
Originally Posted by seapuppy
if it's an mpi engine..it will spin right up to redline...or the rev limiter..whichever is first...SP irate:
Understood, but will it spin to red line/rev limiter at WOT under load?
ss3964spd is offline   Reply With Quote
Old 08-28-2009, 03:04 PM   #10
Admiral

 
seapuppy's Avatar
 
Join Date: Nov 2005
Location: Everett Wa
Posts: 4,681
Default Re: Only getting 4200 rpm @ wot???

provided it's propped properly......yes......my 2700 would hit rev limiter....


SP
__________________

__________________
Don't compare your life to others. You have no idea what their journey is all about.
------------------------
SSN683 Association member
Par Excellence
------------------------------
2008 Bayliner 340 - "Wild Whim"
--------------------------------------
I live in my own little world....but it's okay-they know me here!!!

Avid practitioner of the martial art: KLIK-PAO.
Tap-Rack-Bang

Anyone that sez "Size doesn't matter" has never owned a boat!
seapuppy is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Powered by vBadvanced CMPS v3.2.3

All times are GMT. The time now is 12:38 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2017, vBulletin Solutions, Inc.