The objective of the study was to investigate the spray and combustion characteristics of Jet Propellant- 8 (JP-8) using a high-pressure fuel injector which is capable of up to 250-MPa fuel injection pressure. Experiments were performed in a constant-pressure flow-through combustion chamber at the ambient conditions of 825 K and 6 MPa for the oxygen concentration of 0 and 21%. JP-8 was injected over a range of fuel injection pressures from 50 to 250 MPa for single injection events to establish a baseline operation. Pilot and post injections were used to study the effect of multiple injections on spray and combustion of the high-pressure fuel injector. Both pilot and post injection separation times and quantities were systematically varied. JP-8 spray and combustion events were imaged at 75 kHz using a combination of Mie scattering and OH* chemiluminescence imaging. The Mie scattering results showed that the injector exhibited more vaporization due to enhanced atomization as the injection pressure was increased. For non-reacting multiple injections, the liquid penetration length of the main injection approached close to those of the pilot and post injections with increasing fuel injection pressures. Spray patterns became more uniform both within an injection and across injection events at the higher fuel pressures. The OH* chemiluminescence results showed that both the pilot injection timing and separation time influenced the ignition delay with shorter separation timing and larger pilot quantity resulting in shorter ignition delays. Post injections resulted in additional OH* indicating further heat release with larger gains at higher post injection quantities. These results indicate that the higher injection pressures combined with optimized injection strategies could lead to enhanced combustion.