I cant find him anywhere on the web all i can suggest is you put a page on the Irish page .
 also try mcNulty . i have even looked for the deaths and marriage for the rest of his earlier family and nothing is coming up anywhere .But i did find
McNULTY  Charles  Deaths Dec 1838 in whitehaven if he was about 12 it could be his brother.
McNULTY  Jane  Deaths Mar 1864 in whitehaven  could be his mum
Iv been at it a while now checking all the 1851 census ,cant find Isaac nulty but found Isaac Hultz abt 1829  Whitehaven, Cumberland, England  wife Elinor Hultz abt 1831  Saltham, Cumberland, England .
 then a Jane MC Hultz abt 1844  St Bees, Cumberland, England Granddaughter  living with the Reed ,
Isaac appears again on the 1871 with a reed niece living with then.
have you look at the 1841 census , i was hoping to find him living with a relative somewere that might have lead to were his parents came from.
it looks like a few differant spelling 
McNULTY ,  Hultz,  NULTY , macnuly, 
don't give up we are all up for the challenge 
 
 
                                                 paula