The growing environmental challenges and the rapid depletion of global fossil fuel reserves have driven the urgent need to explore alternative energy sources. In present work, an experimental investigation evaluated the stability of ethanol-diesel blends using jatropha methyl ester (JME) as a co-solvent, alongside engine performance and emissions at varying injection pressures and timings. Stability tests revealed that ethanol cannot blend with diesel without additives, requiring at least 4% JME for one-day stability, with E10B10D80 (10% ethanol, 10% JME, and 80% diesel by volume) blends remaining stable above 10°C. Optimal injection parameters were identified as 2.0 × 10⁷ Pa pressure and 17° before top dead centre (BTDC) under different loads. JME proved effective as an additive, though its cost was higher than diesel, suggesting its long-term viability as fossil fuel resources diminish. Fuel consumption increased due to ethanol's lower calorific value, while thermal efficiency improved at low loads but decreased near full load. Emission analysis indicated that carbon monoxide (CO) emissions were lower at loads above half but higher at lower loads compared to pure diesel. Hydrocarbon (HC) emissions consistently rose with the blend, while a reduction in the nitrogen oxides (NOx) emissions was observed at relatively lower load but increased near full load, showing no consistent trend. The study highlights the potential of JME as a biofuel additive, with its economic feasibility expected to improve as reliance on fossil fuels declines.