According to the 2024 test results of the American Automobile Association (AAA), the Fuel pressure of the faulty ATV of the Fuel Pump during idle speed may go down from the nominal value of 3.5bar to 1.8bar (allowable range ±0.3bar), which leads to the air-fuel ratio of the engine from 14.7:1 to 17.5:1. It raises the temperature of the cylinder to 980℃ (it should be 850℃), and the wear rate of the piston ring is raised to 0.12mm/hour (it should be 0.02mm). Statistics provided by Transport Canada show that ATVs with leaking fuel pumps have a 64% likelihood of stalling when operated off-road. Among them, 23% of the accidents occur on slopes > 15° and may increase the rollover threat up to 3.2 times.
Leakage of the fuel is the crux of the safety hazard. As the Fuel Pump sealing ring gets older (with A hardness loss > 15 Shore A) or the shell cracks (with a crack length > 2mm), the leakage per hour can be 30-50ml. EPA lab simulations project that where the leaked fuel comes into contact with hot exhaust manifold (> 400℃), the likelihood of ignition is 89%, with a spread rate of combustion being 0.8m/s. In Montana’s ATV fire investigation in 2023, 38% of the fires resulted from faulty fuel pumps, with a mean loss of $8,200 per incident (including vehicle and environmental clearance costs).
Differences in gradient occur in performance degradation
Primary failure (20% impeller wear) : The flow rate drops from 120L/h to 95L/h, and the 0-60km/h acceleration time is prolonged by 1.5 seconds (e.g., Polaris Sportsman 850);
Moderate fault (motor carbon brush loss 50%) : The operating current is between 5A and 9A (normal ±0.5A), and the ECU enables the speed-limiter mode (maximum speed at 35km/h).
Total failure: After the oil pressure has descended to zero, the working time of the engine only lasts for 45 to 90 seconds (when there is 20% of fuel remaining in the tank), and dilution of crankcase is more probable (when the concentration of oil and fuel contamination is greater than 5%).
There needs to be economic costs taken into consideration during the entire process. Kawasaki Brute Force 750 in Chuanzhou can be used as an example:
Short-term carryover: Maintenance cost per day is 15 (periodic cleaning of fuel injectors + replacement of filter elements), and the annual cost is 5,475;
Direct replacement: Factory original pump 380 (labor hours included), cost of ownership over 5 years 0.21 per kilometer;
Postponed replacement: If it will lead to the destruction of the high-pressure oil pump (620) and clogging of the catalytic converter (1,100), the cost of repair will increase by 320%.
Regulatory risks cannot be ignored. The leakage rate of ATV Fuel Pump is not supposed to exceed 0.05g/h in terms of the EU Euro 5 norm, and the emissions from the faulty pump are 12-18 times greater than the norm (benzene series concentration 0.8mg/m³ vs.) compared to the stipulated norm of 0.05mg/m³. The New South Wales, Australia, 2024 penalty cases show that the mean road inspection fine for ATVs with defective pumps is $650, and the insurance denial rate is up to 92% (exempt from mechanical failure liability under Clause 4.3.2).
Limited usage strategy in emergency situations
Slow speed on flat ground (< 30km/h) : Maintains oil pressure of 2.0bar through an external 12V auxiliary pump, but only to within 15 kilometers (risk level B);
Direct fuel supply: Emergency supply by hand pump (e.g. Holley 12-802-1), with 15-20 presses per minute. Only for evac (up to 30 minutes).
Electronic bypass: Induces the ECU into limp mode (the oil pressure demand drops to 2.5bar), but can initiate the P0087 fault code, which will lock the ECU.
German TUV durability test shows that after continuous run of faulty Fuel Pump for 24 hours:
The carbon deposit content of the fuel injector increased to 380mg (for new components < 50mg), and the atomization efficiency fell by 41%.
The pressure difference of the fuel filter was raised from 0.3bar to 1.8bar, and the attenuation rate of the flow was 58%.
The float valve on the fuel tank becomes deformed due to negative pressure, and the fault in the fuel gauge increases to ±22% (normal ±5%).
Conclusion: Technically operational for a short time, the safety, economic, and legal risks posed by the faulty Fuel Pump grossly outweigh the short-term comforts. NHTSA recommends that the car be stopped immediately when an oil pressure warning is displayed (instrument light or fault code P0087) and the replacement cycle be controlled within 48 hours in order to avert the risk of system damage.