Older cars are often easier to steal, which is why I installed a fuel pump cutoff switch to protect my cherished old Mercedes.
This simple yet effective modification can significantly enhance your car’s security by disabling the fuel pump and preventing unauthorized use. Here’s a step-by-step guide to fitting a fuel pump cutoff switch:
Tools and Materials Needed
- Test Light or DVOM (Digital Volt/Ohm Meter)
- Wire Strippers
- Soldering Kit
- Screwdrivers
- Kill Switch
- Electrical Tape
- Copper Core Wire (approximately 6 feet)
Steps to Install a Fuel Pump Cutoff Switch
Locate the Fuel Pump Power Supply
- Start by identifying the power supply circuit for your fuel pump. Check your fuse box for labelled circuits, or refer to your vehicle’s operator’s manual. The fuses should be numbered for easy identification.
Install the Kill Switch
- Choose a discreet location for the kill switch where it’s accessible but not immediately visible. Consider placing it in less obvious spots such as the glove box, under the seat, in the armrest compartment, or behind the gear selector boot.
Cut the Fuel Pump Circuit Wire
- Remove the fuse related to the fuel pump circuit and cut the wire downstream of it. With the ignition switch on, check for zero volts to ensure you’re cutting the correct wire.
Wire the Switch
- Connect two wires from the kill switch to the cut fuel pump circuit wires. Ensure your wiring is routed neatly and cut to the correct length. Strip the wires and install heat shielding to protect them from dampness and corrosion.
Solder and Secure the Connections
- Twist the wires together before soldering to create a strong connection. After soldering, slide the heat shielding over the connection and shrink it using heat.
Tape and Test
- Use electrical tape to secure the wiring and prevent any potential short circuits. Replace the fuse and test your work. When the fuel pump is powered, it should hum momentarily, indicating the system is working correctly.
Alternative Options
Fuel pump kill switches can only be fitted to cars with electric fuel pumps, and as many older cars have a mechanical pump, you’ll need alternative options.
1 Ignition Kill Switch: Another option is an ignition kill switch, or dizzy switch, which is fitted in the wire between the distributor and coil. This switch is especially suitable for cars with a distributor.
However, it’s not suitable for modern vehicles equipped with CAN network systems, which may misinterpret the additional wiring as a fault.
2 Battery kill switches: They are a versatile anti-theft option for both older and newer cars. They can be manual or remote-controlled. While manual switches are straightforward, remote-controlled options offer added convenience.
Note that these switches cut all power, which means you’ll need to reset your dashboard clock and radio settings. More advanced models only cut power to the starter, leaving other systems unaffected.
3 Fuel Line Cutoff: A fuel line cutoff valve provides a mechanical solution for vehicles with a mechanical fuel pump. Install this valve between the gas tank and the carburettor.
It’s a simple tap that’s easy to fit but can be tricky to hide. Cut the fuel line, attach the valve, and secure it with clamps. While the engine will start with the tap off, it will stall shortly after.
Conclusion
Installing a fuel pump cutoff switch is an effective way to deter theft and secure your vehicle. Whether you choose a fuel pump cutoff switch, ignition kill switch, battery kill switch, or fuel line cutoff valve, each option has its benefits and considerations.
Following these steps can enhance your car’s security and enjoy peace of mind.
Related Questions
How to bypass a kill switch on a car: Remove both connectors from the kill switch and use a piece of wire to connect both ends together, secure with tape, until a more permanent repair is made.
DIY car theft prevention? A great DIY theft prevention quick fix is to remove the fuel pump relay. It will fit easily in your pocket. Another option is to remove your HT coil wire. It, too, will fit easily in your pocket. Your car will go nowhere without gas or spark.
You may find the following links useful:
Are older cars easier to steal?
- About the Author
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John Cunningham is an Automotive Technician and writer on Rustyautos.com. He’s been a mechanic for over twenty-five years and has worked for GM, Volvo, Volkswagen, Land Rover, and Jaguar dealerships.
John uses his know-how and experience to write articles that help fellow gearheads with all aspects of vehicle ownership, including maintenance, repair, and troubleshooting.