496 Mag HO Fuel pressure issue

[25Outlawboy]

It’s use is explained in the service manual. The high pressure pump needs to be cooled, this paste allows that to happen.
It comes with the kits the S.B. listed, not sure if it’s included when you buy just the pump.
It’s white in color and makes a mess if you try to replace the pump while the cool fuel 2 is still on the engine.

Might be a good idea to read the manual before attempting the pump replacement, there is a bit more to this job than just the pump.

Thank you for the followup Muc.. My boat has had both fuel pumps replaced before I got it and there is not any of that white paste on the new pump. FYI.. I did find a substantial fuel line blockage (fuel tank to boost pump) a few weeks prior and did replace the fuel line but have same fuel/running issue. Boat had been run well over 12 hours flawlessly before having any running issues, I found that fuel line issue after I started having the issues. Question is, could that restriction have caused the Hi Pressure pump to start to fail prematurely? Also, do you have a link to the info you describe in the the service manual pertaining to the HP pump replacement and the paste? Thank you

 

[25Outlawboy]

you cant physically see it unless you unscrew the tube from the fitting.
when you probed the tank end with a wire did it go all the way to the 90 fitting, Eg: 11 inch tube, 11 inches of wire

Mine is a plastic semi clear pickup tube that does not screw onto the 90 degree fitting but rather pushes on to a barb like 90 degree fitting. I can see all the way up into the fitting so making sure the fitting is clear is easy to verify. All clear form tank pickup end thru to the ASV.

 

[muc]

Thank you for the followup Muc.. My boat has had both fuel pumps replaced before I got it and there is not any of that white paste on the new pump. FYI.. I did find a substantial fuel line blockage (fuel tank to boost pump) a few weeks prior and did replace the fuel line but have same fuel/running issue. Boat had been run well over 12 hours flawlessly before having any running issues, I found that fuel line issue after I started having the issues. Question is, could that restriction have caused the Hi Pressure pump to start to fail prematurely? Also, do you have a link to the info you describe in the the service manual pertaining to the HP pump replacement and the paste? Thank you

A suction side restriction can cause cavitation, and that can be bad for pumps.

Mercury Marine doesn’t allow me to post links to copyright protected information. Maybe someone else will.