Fuel pumps intended for use with Electronic fuel injection (EFI) and carburetor (Carb) systems are subject to two basic requirements: wide pressure range and adjustable flow rate. Take the Holley 12-327-11 fuel pump example. Its pressure output range is from 3-7 psi (carburetor spec) to 45-60 psi (EFI spec), and dynamic switching is achieved with an external regulating valve (accuracy ± 0.5 psi). The flow rate is calibrated to 150-300 L/h (120 L/h carburetors and 200 L/h EFI) with a maximum adjustment rate of up to 90% (tested in 2023 by SAE). In the 2024 SEMA modification show, this pump was applied in the 1970 Chevrolet Camarro (carcartor) and LS3 engine (EFI) hybrid project. The fluctuation of fuel pressure was regulated to within ± 1 psi, and air-fuel ratio deviation was ≤ 0.5, confirming cross-system compatibility.
Pressure and flow rate compatibility must consider both material strength and design redundancy. Walbro GSL392 has a twin-turbine blade design (impeller thickness of 2.5mm), operates at 58 psi pressure (flow rate of 255 L/h) in EFI mode, and reduces the pressure to 5 psi (flow rate of 130 L/h) by a bypass valve in carburetor mode. Wheel bearing load of 300 N to 80 N, the rate of wear decreased by 60% from 1000 hours to 2500 hours (life). The Honda CB750 modification case indicates that with the application of this pump, the level of carburetor overflow dropped from 8% to 0.5%, and fuel economy in EFI conditions was better by 12% (fuel consumption dropped from 7.5L /100km to 6.6L /100km).
The cost-benefit analysis shows the economic advantages of the general pump. AEM 320 l/h price ($280) vs buy individual EFI pump ($200) + carburetor pump ($120) save 40%, and take up 50% less installation space (40 mm x 80 mm size Φ vs The standard dual-pump set (100mm × 150mm). But it should be noted that in the EFI mode, pulsation damper ($50) needs to be fitted to suppress pressure oscillations (± 5 psi →± 1 psi), the fuel injector life would otherwise decrease from 100,000 kilometers to 60,000 kilometers (tested by Hot Rod Magazine in 2024).
Environmental compliance with law is another obstacle. Carburetor system is common with old vehicles (e.g., the Ford Mustang of 1965) and requires SAE J30R10 fuel hose specification (alcohol-resistant fuel), while the EFI system requires Euro 7 evaporation emission standard (leakage rate ≤ 0.05mg/h). The Edelbrock 1795 fuel pump has fluororubber sealant (with temperature resistance -40℃ to 150℃) and double-certified design. During the hot test (50℃), leakage rate of carburetor mode is ≤ 0.1mg /h and leakage rate of EFI mode is ≤ 0.03mg /h. Become the first CARB-certified general-purpose pump on California market (launched in 2023).
The application of the event verifies the reliability of the device under severe working conditions. The NASCAR team used the Bosch 044 fuel pump (with pressure regulating valve modified on it) to switch between the carburetor mode (6 psi) and EFI mode (65 psi). At the constant 24-hour track test, flow error was ≤ ±3%. Armature temperature rise is controlled at 40℃ (max 80℃ for standard pumps). However, for the case of high-ethanol fuel (E85), an additional robustification of the impeller coating (silicon carbide, cost + 30%) is required to prevent wear and corrosion (HFRR test value from 600 μm to 150 μm). In case customers find both upgrading new power and bringing back old cars worthwhile, General Motors Fuel Pump is a viable and reliable solution.