We investigated the effects of biodiesel fuel with methanol and triglyceride on diesel engine performance in agricultural tractors by applying loads to the engine crankshaft using a dynamometer. In test by using biodiesel fuel with a high content ratio of methanol, the engine torque has decreased at all engine speeds due to decreased fuel injection value. It appears that the fuel injection volume decreases when vaporized methanol is added because the fuel temperature rises during combustion.