  Spectrophotometric data of the young planetary nebula M 3-27, from 2004 to
2021, are presented and discussed. We corroborate that the H I Balmer lines
present features indicating they are emitted by the central star, therefore He
I lines were used to correct line fluxes by effects of reddening. Important
variability on the nebular emission lines between 1964 to 2021, probably
related to density changes in the nebula, is reported. Diagnostic diagrams to
derive electron temperatures and densities have been constructed. The nebula
shows a very large density contrast with an inner density of the order of
10$^{7}$ cm$^{-3}$ and an outer density of about $10^3 - 10^4$ cm$^{-3}$. With
these values of density, electron temperatures of $16,000 - 18,000$ K have been
found from collisionally excited lines. Due to the central star emits in the
H$^+$ lines, ionic abundances relative to He$^+$ were calculated from
collisionally excited and recombination lines, and scaled to H$^+$ by
considering that He$^+$/H$^+$ $=$ He/H$ = 0.11$. ADF(O$^{+2}$) values were also
determined. Total abundance values obtained indicate sub-solar abundances,
similarly to what is found in other comparable objects like IC 4997.
