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Stumped on 2012 Massimo EFI MSU700 Issues


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I'm hoping someone can help me out on this one before I pull out what's left of my hair. I bought a 2012 EFI MSU700 about a month ago and was told that "it floods out sometimes, and needs a fuel pump".

Here is where I am with it...

The machine will start MOST of the time. I have had it not want to start a couple times. It would just crank and crank but not fire. The machine idles fine, and in low gear drives fine but every now and then it will hesitate and almost feel like it is surging and sometimes it will sometimes backfire. In high gear it will drive fine but at around 25mph it starts to hesitate and bog down and backfire. I do have my seatbelt on as I have heard that can trigger a limp mode.

After running for just a few minutes, the exhaust headers will be glowing red. This is what baffles me as if it is a lean condition and starving for fuel, but the spark plug when I have checked it has been black.


It will smoke on startup and during acceleration and seems to get better after the engine warms up. I'm not sure if it actually gets better after it warms up, or the oil is burning off enough to make it not smoke as bad. The machine does not seem to smoke during idle or very slow acceleration.

The dipstick verifies that I am burning oil also. I am thinking this may be a ring issue? I did not see any signs of oil in the airbox.


When I replaced the fuel injector and had the fuel line disconnected, I turned the key on and off several times and it seemed as though I had a good amount of fuel coming out of the fuel line. It would "prime" for 4-5 seconds and then stop. The fuel also looked/smelled to be OK.

I have replaced the fuel injector, the spark plug, and changed the oil and filter and it has made no difference. I have not replaced the air filter as it seems to be fairly clean. I didn't notice any visible cracks on the intake boots, but I also have not removed them to examine them all the way.


Is it possible that the fuel pump actually is an issue and starving the engine for fuel, leaning it out, but the fact that its burning oil is making the plugs black? Is it running rich and dumping excess fuel into the exhaust? Is this an exhaust valve stuck open? Any help would be GREATLY appreciated as I would prefer to approach this with a plan instead of just throwing parts at it :)

Thank you!


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  • stankholio changed the title to Stumped on 2012 Massimo EFI MSU700 Issues

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