377 Mag low WOT RPM

[Matt Kolinski]

I recently bought a 2007 Sea Ray 240 Sundeck. It has a 377 mag (6.2L) with Bravo3 outdrive (original props). The WOT RPMs is only 4500 and it only tops out at about 46 mph. I thought that full throttle for the engine should be more around 5000 (between 4800 and 5200). The only thing I have done is confirmed that the throttle cable is adjusted properly. Any ideas on what to troubleshoot?

 

[guyjg]

Pull the spark plugs and read them...you want to see a medium brown color. If one or more are not brown then you have found the suspect cylinders. White is too lean, black is too rich.

 

[Docksidemarineservices]

Put a fuel pressure gauge on it, you will probably find that the pressure is climbing over 40lbs while at idle. If this is happening it means the fuel pressure regulator on top of the fuel module is plugged up with the paint that is coming loose from inside the module. Two 8mm or 5/16 screws hold the regulator in. It is silver in color and has a vacuum line attached, Easily removed and cleaned. Re check your pressure after wards.

Also change both filters in the module, 10mm screws.

 

[bondo]

I recently bought a 2007 Sea Ray 240 Sundeck. It has a 377 mag (6.2L) with Bravo3 outdrive (original props). The WOT RPMs is only 4500 and it only tops out at about 46 mph. I thought that full throttle for the engine should be more around 5000 (between 4800 and 5200). The only thing I have done is confirmed that the throttle cable is adjusted properly. Any ideas on what to troubleshoot?

Ayuh,.... Do a Tune Up, 'n Compression test of the motor to see if it's puttin' out the Power it should be,....

If it checks out, Ok,...
Change the props,... The PO may have over-proped it...