Honda Grom 125 (MSX125) usually adopts an integrated Fuel Pump design in the fuel tank. The original equipment manufacturer (OEM) part number is Fuel Pump HG3-Z52 (which may vary depending on the year). The rated working pressure range is between 40 and 50 kPa (5.9 and 7.25 PSI), the flow rate is approximately 8 to 10 L/h, the weight is about 280 grams, and the size and specification should match the internal installation cavity of the fuel tank, with a diameter of about 70mm and a height of no more than 130mm. The 2020 industry report analysis pointed out that in such cases of fuel system failure of small motorcycles, 30% were due to the blockage of the fuel pump filter screen, resulting in a flow rate drop of more than 40%, or the risk of start-up failure caused by a pressure lower than 35 kPa rose to 85%.
The market-compatible replacement options mainly include Aftermarket options with prices ranging from ￥150 to ￥300, such as Acerbis 3801 or All Balls AF-PUMP-007, which maintain a pressure output of 45±5 kPa and a flow specification of 7.5-9.5 L/h. Temperature tolerance range: -25°C to 85°C. Test data shows that after installation, the efficiency loss is controlled within 3%, and the average return rate increases by 15% (compared with the higher unit price of original factory parts). The 2022 European Motorcycle Maintenance Survey Report indicates that 70% of technicians recommend using after-sales fuel pumps that meet the ISO 15886 shock absorption standard (peak acceleration 10-15g), which can extend the product life cycle to 15,000-20,000 kilometers and reduce the probability of failure caused by vibration by 50%.
In terms of cost-effectiveness, the budget for independently replacing the fuel pump assembly (such as the pump core) is approximately ￥50 to ￥120, which saves 60% compared to replacing the entire assembly (￥200 to ￥400). However, it requires professional technicians to disassemble the fuel tank, with a labor cost of around ￥150. U.S. consumer data shows that 65% of users replace their fuel pumps every 3 to 5 years. After replacement, the combustion efficiency is optimized to 92% of the theoretical value, and the fuel economy per 100 kilometers is improved by approximately 0.3 liters. According to the maintenance records of Honda dealers, after the 2021 model Grom 125 adopted the improved metal impeller fuel pump, the average annual failure rate dropped from 5.2% to 1.3%.
A typical case reference: According to the statistics of the 2023 Southeast Asia Motorcycle Forum, among the 15,000-kilometer mileage vehicles causing engine stalling accidents due to fuel pump failure, the proportion in tropical high-temperature areas (>35°C) reached 68%. After modifying a high-performance fuel pump such as Walbro GSL392 (with a 20% increase in flow rate to 12L/h), the peak power of the engine slightly increased by 0.5-0.8kW, and the standard deviation of torque fluctuation improved by 30%. The paper in the authoritative journal “Small Engine Technology” points out that the flow accuracy deviation of the fuel pipeline needs to be controlled within ±2%; otherwise, the dispersion of the air-fuel ratio will increase by 25%, and the risk probability of exceeding the emission standard will increase by 40%. When choosing a replacement plan, it is essential to verify that the pressure parameter difference does not exceed ±3kPa to ensure the stability of system integration.