90HP booging

[eedwards]

My 1975 90HP is booging after a few seconds at full throttel and when i hit a lot of wake.
If i back off just a little i can cruise and it will rarely do it.
I replaced the fuel pump diaphram but its still doing it.
ANY IDEAS?

 

[eedwards]

Re: 90HP booging

Hello anyone there?

 

[eurolarva]

Re: 90HP booging

Might want to first start with a compression and spark test for all units. Could be a blown head gasket or a cylinder not firing. If both tests show good next I would start with the carbs and the rest of the fuel system. Not sure on that motor because you did not post a model number but if it has a fuel recirculation system it might be plugged.

 

[Frank Acampora]

Re: 90HP booging

Definitely a fuel delivery problem. Start right at the tank and progress firward checking to make sure there are no restrictions. Bogging down when crossing wakes tells me that fuel is not getting picked up in rough bouncing conditions, and the tank and pick-up are suspect. It is also possible that carb floats are sticking and causing the same problem, but I lean toward the tank.
If you look closely, the linkage advances timing almost all the way without opening the carb butterflies very much until the last 1/4 of control lever travel. Then BANG! the butterflies open fully and fuel demand rises sharply. That's why if you back off slightly, the problem goes away.

 

[eedwards]

Re: 90HP booging

Well i did everything still the luck
I wonder if the wrong plugs are in anyone know what the right ones are?