hey i have a honda d15b3 honda civic 93 hatch,just finish doing some mods to it,but i have a problem i still havent managed to fix yet,

my car turns back on after i turn it off,and stays on for about 1-5 seconds.and then motor turns back off again???i do not have a clue y or whats wrong?

please if any1 has had the same problem,or knows the solution.please comment thanks