Massimo 2017 MSU500 won't idle when fuel is not topped off.

[David Trost]

Interesting problem.   My Massimo runs great - but when the fuel level drops just a bit, it just stops.    It restarts easily, but I have to keep my foot on the accelerator pedal.   When I top it off with gas, it again runs fine.   I already replaced the fuel pump, but that didn't work.

Thanks for your help!

[Dan B]

If a pickup tube in the gas tank were disconnected or maybe cracked, that could explain why the engine quits after the fuel level drops (to a point where the fuel pump is pumping air).  The fuel pump draws fuel from the bottom of the tank.  But that doesn't explain why the engine runs if you hold a little accelerator pedal.  Is the fuel tank vent tube plugged somewhere between the fuel tank and the charcoal canister?  Remove the fuel filler cap to see if a vacuum in the tank is causing a loss of fuel supply.  Is the carburetor getting adequate fuel?

[Dan B]

I just watched a YouTube video on your fuel gauge problem.  Might or might not be of help.

https://www.youtube.com/watch?v=dy6IQOE5UEA

On your other problem with the engine not running when fuel is slightly low, make sure your fuel lines (supply and return) are not swapped on top of the fuel pump.  I don't know if it is physically possible, but it's worth checking out.

[Randy Stevens]

On 11/8/2020 at 10:35 AM, David Trost said:

Interesting problem.   My Massimo runs great - but when the fuel level drops just a bit, it just stops.    It restarts easily, but I have to keep my foot on the accelerator pedal.   When I top it off with gas, it again runs fine.   I already replaced the fuel pump, but that didn't work.

Thanks for your help!

Try blowing out injector.  Mine  did same thing. Had plastic particles in it I’m guessing from inside gas tank as it’s all plastic anyway, maybe a burr from injection machine that form it??  Mine since idles fine after warming up a few seconds. Hope this info helps!