2010 won't start without battery

[Gr8Dank]

Fuel pump!!

[darrengee]

Well......what was the fix?  My bike is doing the same thing (2009 KX450F)

[thorarinnarni]

I'm having the same problem with my KX450F 2011. Only starts connected to a battery. I've replaced the capacitor and that was not it.

I'll measure my DC and AC voltages tomorrow and see what that does. But could the bike be running if the rectifier is bad ?

[heegeri84]

Im having same problems, only get about 5v To fuel pump when kicking and no prime at all. When i add 12v battery To capacitor plug, it starts To prime and no power loss at fuel pump plug. Went trough all connections and they seems To be clean. Tried with 3 differend capacitor. 

Been thinking To give up and add battery with power switch beside capacitor. 

[Kx450fnoob]

I just went through this on my 09 and it was a bad magneto. Identical symptoms.