Fuel Pump clogging may be identified by the reduction of fuel pressure and the malfunction of the engine. According to the SAE J2719 standard, the normal operating range of fuel pressure is 3.0-4.5 bar. If pressure is below 2.5 bar and flow rate attenuation is ≥30% (e.g., original factory flow rate goes down from 300 L/h to 210 L/h), it can be a sign of blockage. For instance, the statistics of the North American Automobile Association (NADA) in 2023 reveal that for Fuel pressure less than 2.8 bar vehicles, 67% have clogged Fuel Pump filters (with pore diameters reduced to less than 5 μm), and the median repair price is $380, 55% more than in conditions without clogging.
The power loss of the engine is a direct manifestation. When the Fuel Pump flow rate is downgraded from 300 L/h to 180 L/h, the maximum power of the turbocharged engine reduces by 18%-22%, and the 0-100 km/h acceleration time is up by 1.5-2.0 seconds. During the 2022 Dakar Rally, the Fuel pressure in Toyota Hilux suddenly dropped from 4.2 bar to 2.1 bar owing to the clogging of the Fuel Pump filter screen by sand and dust. This resulted in the increase in fluctuation of the torque output at the high-speed range (≥5000 rpm) from ±3% to ±12%, which resulted in a loss of 8 minutes and 44 seconds in single-stage performance.
Unstable idling and hard starting are common symptoms. If the blockage causes the fuel supply pressure to deviate more than ±1.0 bar, the air-fuel ratio correction rate by ECU increases from a typical 20 times a second to 50 times a second, and cold start success rate decreases from 98% to 72%. Volkswagen Group’s 2023 technical report indicates that when the EA888 engine is equipped with a clogged Fuel Pump, the start-up time in -10°C temperatures is increased from 1.2 seconds to 3.5 seconds, and the battery’s maximum load current is boosted from 180A to 250A (shortening the battery life by 23%).
The abnormal rise in fuel consumption was found to be statistically significant. When the fuel pump flow rate decreases by 25%, the fuel consumption of the 1.5T engine goes up from 6.5L per 100 kilometers to 8.1L (an increase of 24.6%). Based on a calculated estimate on the assumption of an average annual driving distance of 15,000 kilometers, the owner will have to pay an additional amount of approximately $570 on fuel expenses. Clogging of filters was shown to raise the diameter of fuel injection atomization particles from 20 μm to 55 μm, lower combustion efficiency by 19%, and boost the exhaust concentration of unburned hydrocarbons (HC) from 50 ppm to 220 ppm in a 2024 study published in Automotive Engineering. The normal running noise of Fuel Pump is 45-55 decibels (dB), and the maximum in case of idling of the impeller due to blocking is 75 dB (frequency is centered in 2000-3000 Hz). As an illustration, during the year 2023 owners’ survey for the Ford F-150 vehicle resulted in the report that 85% of occurrences of blockages in the Fuel Pump were further marked by higher frequency irregularities, and by acceleration in vibration of steering wheels from 0.3g to 1.2g (having 0.5g threshold perception).
The test process to take is merely watching with the fuel pressure gauge. After connecting the mechanical pressure gauge, if the pressure in full throttle case is below 2.8 bar or pressure decay exceeds 0.5 bar in 10 seconds, it can be stated that there is a blockage. Measurement outcomes of the Bosch laboratory show that the pressure transient drop amplitude of the choked Fuel Pump during full acceleration is 1.8-2.5 bar (normal pump ≤0.6 bar), and the likelihood of triggering the ECU fault code P0087 increased from 3% to 89%.