At a loss with 1976 merc 165hp inline 6

[Roach12]

So my boat sat for 6 years before I inherited it so I went through everything and all seemed good so I changed all the fluids and took it to the lake. It fired up with a little starter fluid and ran around the lake for about a half hr but the engine seemed to run a little rough. Took it out a few more times that year and it would randomly die on me or die when I got into higher rpms. Since then I have coated the old tank after removing rust with por15 and replaced the entire fuel line, fuel pump, new spark plugs, and cleaned the carb but now sometimes it won’t even start and if it does it seems really rough. Not sure what to do at this point.

 

[TyeeMan]

Have you changed point(s) and condenser, set the timing and dwell to the proper settings? These are important ignition items that need occasional attention.

 

[Roach12]

Changed points and condenser to electronic ignition.

 

[Bondo]

and cleaned the carb

Ayuh,..... Welcome Aboard,.....I donno how gasoline proof por-15 is,.....

Pull the fuel filters, 'n look for any crud,......
'n the carb probably needs a full on rebuild, or possibly replacement,.....

 

[Scott Danforth]

Since then I have coated the old tank after removing rust with por15

POR 15 or the fuel system sealer from POR15? I have had problems with both.

you would have been better off with red kote

As Bondo stated, pull the fuel filter and look for crud