Mercruiser Engine RPM is capped.

Max Lin

New Member
Jul 7, 2013
13
Taiwan
Boat Info
310 Sundancer 2008
Engines
350 Mercruiser V-drive
Need some help here. I have a 2008 310 Sundancer with 2 x 350 MAG MPI 5.7 Mercrusier engines. I just changed the manifold and exhaust to fix the overheating problem and here comes another issue which never happend before. When I speed up the throuttle, I heard a beep from computer and then the RPM was capped at 2500. I went back to shipyard and have someone to check my engines with computer. It computer indicates the engine is at "nuture" (actually the engines were geared up) without any other error messages. RPM of both engines cannot go beyond 2500 now. Looks like some safity control function was triggered to protect the engine but don't know to reset the engines back to normal. We don't have many experienced boaters here, any advise is very much appreciated.
 
You most likely have a smartcraft with cruise control. If the cruise control is engaged and set at 2500 rpm that is all you will get. The tell tale sign is when you push the sticks forward and get that beep. When you pull them back you probably get another beep.

This is what your problem sounds like. I use my cruise control all the time and this could be it.
 
yes, i got another beep when i push back the stick.. i never use the curise control before but I will go back to check tomorrow. thanks for the help..
 
Hi Gary, you are right, my cruise control was enabled at 2530RPM, that is the reason making my RPM capped. Thanks for advice.
 
Is that cruise control or limp home? 2500 is not a healthy RPM for those engines.

I'm curious as to what you mean by that? He's going to be burning through fuel like mad at 2500 RPM (because he is plowing rather than on plane), but as far as I know, there is nothing detrimental to the engine. Best fuel economy is around 3500 RPM for generally for all gas engines, and it's harmful to run at excessive RPM for extended periods.....can you elaborate?

That's what I get for posting after great morning sex......OK......That's a lie.........I really just wasn't awake.

I meant just what you posted. He is going to be plowing through the water somewhere between hull speed and trying to overcome the bow wave to get on plane. Fuel consumption will be obnoxious. IMHO, it is not healthy for the engines because even though marine engines work hard all the time, they work hardest when a planing hull is getting over that hump. That kind of stress could only serve to shorten the longevity of the engine. I see it as different then running at WOT all the time albeit both will end you up in the same expensive situation. I've been told to liken a marine engine to running a car up hill in first gear all the time. Add that stress to running with the boat at that attitude and you are going to stress the entire drivetrain even more. Stress creates heat. Heat can lead to premature failure of components.

Just one man's amateur opinion.

I still want to know about cruise control and if that is what it is, why is it set at an RPM that is so far off the mark for normal cruising in that boat with that engine package.

Is is cruise control or limp home?
 

Forum statistics

Threads
112,950
Messages
1,422,861
Members
60,932
Latest member
juliediane
Back
Top