NO GO Mariner 40HP twin carn 2 stroke stuutering and failing at high rpms

[PatrickMonahan]

Mariner 40hp Surging at WOT and dying off at high RPMS HELP

I have a new problem with y Mariner 40hp that it is surging at WOT and slowly dies down in the revs until it stops, I checked the plugs and they are wet fouled, also the compression seems to be 110psi on both cylinders, i dont know what is causing it to die down in revs completely until it stops, it is very intermittent, the carbs were took apart and seem to be fine so its not that, its a fuel starvation problems, any suggestions?

 

[racerone]

Run with a " known to be good " hose and tank.

 

[PatrickMonahan]

Got a mechanic to check the fuel pump today and he found a hole on the diaphragm inside the fuel pump, hopefully this is the problem, i was also told that you leave out a plate and spring because if you put it back i, it will damage the new modified diaphragm

 

[Texasmark]

My diaphragms came in a kit with all the whistles and bells, plus, believe it or not, directions.

 

[PatrickMonahan]

After replacing the fuel pump diaphrams and gaskets on the fuel pump, took the boat out today and it rain at full throttle nice for 15-20 seconds and then it started to stutter at high revs, about two minutes later the engine completely cut out on me but started easily again and failed, it never turned off before i installed a thermostat in in that works because the previous one was broke open and therefore the engine was always cool, could the coils be breaking down, it is a dual coil motor with a mitsubishi logo on the coil and is about 35 years old, would the coil heat up from the engine and break down, the fuel pump and carboretor have been completely ruled out so it must be something else now but what i dont know.... does anyonew have any suggestions that they could add thanks

 

[yzf125]

You have 3 threads on this !!!!!!!!!!!!!!

 

[WIMUSKY]

Merged threads........

WIMUSKY