The fuel pump vacuum switch is a critical component in fuel systems, particularly those with secondary pumps. It plays a vital role in maintaining proper fuel pressure and preventing engine starvation, especially in high-performance or boosted applications. This comprehensive guide delves into the purpose, technical specifications, and various options available for fuel pump vacuum switches, providing a valuable resource for DIY enthusiasts and automotive professionals alike.
Purpose of the Fuel Pump Vacuum Switch
The fuel pump vacuum switch is designed to activate secondary fuel pumps based on engine vacuum levels. It ensures that the secondary pumps are triggered when the engine requires additional fuel pressure, typically above a certain boost level (e.g., 4-5 psi). This switch is essential for maintaining proper fuel pressure and preventing engine starvation, which can occur in high-performance or boosted applications where the primary fuel pump may not be able to keep up with the increased fuel demand.
Technical Specifications of Fuel Pump Vacuum Switches
Honeywell Pressure Switch (H-77030)
- Aerospace-grade Trigger Switch: The Honeywell H-77030 pressure switch is designed for secondary fuel pump activation, ensuring reliable and consistent performance in demanding automotive applications.
- Gold-plated Internal Contacts and Kapton Diaphragm: The internal components of the H-77030 switch are engineered for long-term durability and resistance to wear, providing a dependable solution for fuel system control.
- Preset for 4 psi Actuation: The H-77030 switch is preset to activate the secondary fuel pump when the boost pressure reaches 4-5 psi, ensuring the engine receives the necessary fuel supply during high-demand situations.
- 1/8 NPT Male Interface: The switch features a 1/8 NPT male interface, allowing for easy integration with push-on boost/vacuum hoses and fittings, simplifying the installation process.
- Optional Sealed Connector and Wiring: The H-77030 switch can be equipped with a sealed Aptiv (Delphi) Metri-Pack 280 connector and 15 feet of 18-gauge bonded wire, providing a complete and weatherproof solution.
- Optional Barb Fittings: The switch can be ordered with black anodized barb fittings for 1/4″ or 3/16″ inside diameter hoses, offering versatility in fuel system plumbing.
Inline Vacuum Valve Fuel Pump Petcock Switch
- Fits Various Engine Sizes: This inline vacuum valve fuel pump petcock switch is designed to work with a wide range of engine sizes, including 50cc, 125cc, 150cc, and 250cc.
- Compact Dimensions: The switch measures 5.51 x 4.45 x 1.57 inches, making it a space-efficient solution for fuel system installations.
Vacuum Switch for Scooter and Gokart
- Inner Vent Diameter: 0.15 inches
- Outer Vent Diameter: 0.25 inches
- Fits Engine Sizes: 149cc, 150cc, 200cc, 249cc
Bypassing the Fuel Pump Vacuum Switch
If the VRO (Vapor Recovery Overflow) system has been removed and a regular fuel pump is installed, bypassing the vacuum switch might be possible. However, it is crucial to ensure that the fuel pump can supply the engine adequately beyond the boost level where the secondary pumps would normally be activated. Failure to do so may result in engine starvation. Additionally, the fuel lines should be checked to ensure they are full of liquid fuel for quick pressurization.
Other Vacuum Switch Options
In addition to the Honeywell H-77030 pressure switch and the inline vacuum valve fuel pump petcock switch, there are other vacuum switch options available for various applications:
| Product | Specifications |
|---|---|
| Inline Vacuum Valve Fuel Pump Petcock Switch | – Fits engine sizes: 50cc, 125cc, 150cc, 250cc – Package dimensions: 5.51 x 4.45 x 1.57 inches |
| Vacuum Switch for Scooter and Gokart | – Inner vent diameter: 0.15 inches – Outer vent diameter: 0.25 inches – Fits engine sizes: 149cc, 150cc, 200cc, 249cc |
These vacuum switch options provide alternative solutions for maintaining proper fuel pressure and preventing engine starvation in various powersport and small engine applications.
References
- Fore Innovations. (n.d.). Honeywell Pressure Switch. Retrieved from https://www.foreinnovations.com/product_p/h-77030.htm
- Fore Innovations. (n.d.). Pressure/Vacuum Switches. Retrieved from https://www.foreinnovations.com/category_s/436.htm
- Amazon. (n.d.). New Vacuum Fuel Pump Shut Off Switch Valve Petcock for Scooter Gokart. Retrieved from https://www.amazon.com/Vacuum-Switch-Petcock-Scooter-Gokart/dp/B07DW16FLT
- Amazon. (n.d.). Inline Vacuum Valve Fuel Pump Petcock Switch for GY6 50cc 125cc 150cc 250cc Roketa Sunl Taotao ATV Scooter Moped 4 Port. Retrieved from https://www.amazon.com/Inline-Vacuum-Petcock-Switch-Scooter/dp/B09FZ2QG1T
- BBC Boards. (2018, July 26). XP 150 Fuel Pump – Vacuum switch question. Retrieved from https://www.bbcboards.net/showthread.php?t=919827
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