'65 merc 35hp boggs down @ high speed

[Dekayed]

I have a 65 merc 350 (35hp). After running at 3/4 - full throttle, it begins to bog and sputter after about 10 minutes. If I turn engine off for awhile the problem goes away until I open it back up. I have a feeling its a cooling issue. I have changed the water pump, impeller and all cooling seals (had to change shaft too). I was hoping that this would fix the problem. When I first ran the boat after repairs there was no water comming out the telltail. I blew air into it with a compressor and it slowly comes out now. The boat purrs like a kitten at trolling speed.. Any suggestions would be apreciated.<br /><br /><br />Thanks.

 

[Chinewalker]

Re: '65 merc 35hp boggs down @ high speed

Hi Dekayed,<br /> Is the motor actually getting hot? You should be able to place your hand on the exhaust side cover while the motor is running and you should not burn yourself. Also, some water may exit the exhaust relief just below the lower cowling trim.<br /> A bogging/sputtering is more likely a fuel issue. Perhaps the fuel pump needs to be rebuilt? Maybe you have a condenser breaking down, or perhaps a coil? We'll need more information before we can give you a solid diagnosis...<br />- Scott

 

[yclip]

Re: '65 merc 35hp boggs down @ high speed

I am having the same problem with my 50hp Merc. I was told it is most likely the fuel pump diaphram.<br />fine up to 3/4 throttle then it bogs and coughs.

 

[Dekayed]

Re: '65 merc 35hp boggs down @ high speed

hmm never thought of a fuel issue. I will have to check if it is actually getting hot. Will be a few days before I can get back to camp but ill let you know the minute i put it back on the lake. Thanks