Recently, the combustion chemistry of tetrahydrofurfuryl alcohol (THFA), a potential biofuel, was investigated in a stoichiometric 20 mole-% THFA/methane co-fueled premixed flame at 5.3 kPa by our group [Tran et al. Proc. Combust. Inst. 38 (2021) 631-640]. With regard to this, we continue to explore further the combustion chemistry of this biofuel in order to understand the influence of THFA doping amounts on the flame chemistry of its mixture with methane, and the impact of the alcohol function of THFA on the product spectrum compared to its non-alcoholic fuel counterpart, i.e. 2-methyltetrahydrofuran (MTHF). To accomplish the above said objective, a methane flame, a 10% THFA/methane flame, and a 20% MTHF/methane flame were additionally analyzed at similar conditions using gas chromatography for quantitative species detection and NO-LIF (Laser Induced Fluorescence) thermometry. More than 40 species (reactants, CO, CO2, H2O, H2, and about 14 hydrocarbons as well as 26 oxygenated intermediates up to 5 carbon atoms) were quantified for each doped biofuel flame. The product distributions and consumption pathways of THFA are similar for the 10% and 20% THFA doped flames. The maximum yields of most products increase linearly with the amount of doped THFA. However, some species do not follow this trend indicating interaction chemistry between methane and THFA, which is found to be mainly caused by reaction of the methyl radical. The difference in chemical structure in THFA and MTHF has no notable impact on the mole fractions of CO, CO2, H2O, and H2, but significant differences exist for the yields of intermediates species. The doped THFA flame produces more aldehydes, alcohols, and ethers but it forms clearly less ketones and hydrocarbons. A slightly upgraded version of our previous kinetic model reproduces most experimental data well and it is able to explain the observed differences in intermediate production.