Now I'm not a mechanic... (Unlike some :S ) But I'm gunna disagree on this one...
Cause... The spark doesn't burn the fuel... The spark starts the fuel burning (I thought) and then the flame front ignites the rest of the charge...
So, tiny spark may not be perfect, but it will either ignite, or miss... Not just burn some of the fuel and spit the rest out...
Also, with low voltage, the injectors wouldn't be opening up as much anyway, so there would be less fuel than usual... (depending on ECU (the car does have EFI doesn't it Andrew ))
I'm guessing timing and / or fuel pressure and / or tune...
/awaits proof of my stupidity...