MAF QUESTION 240sx 90

[maik21]

im a owner of a 240sx 90, and theres a question for you....

how i know when i should remplace my maf?? my output mafs at 750rpm is 1.45 volts aprox. recently my car dont charge the battery and my mechanic replace voltaje regulator, but he do a swap from oem voltaje regulator.... he cut the circuit from alternator and put an cheap voltaje regulator near to intake manifold..... what amount of voltaje is supply to the maf?? 13.4v, 13.8 volts ? 14volts ?? ... if my maf input voltaje is upper than the required, it will affect the output voltaje?? ... maybe the cause of my 1.45 volts is the greates voltaje into the input maf!!... help with this please!! =)