Adding electronic fuel injection (EFI) is a great way to improve the performance and efficiency of your classic ride. Of course, it isn’t as simple as bolting a fuel injection unit onto your intake and then all is well. There are some other crucial aspects that need to be considered for an EFI system to function properly. To make sure that you get the best results with your install, we talked to the Jason Oberhelman, operations manager at FiTech, and got some tips to ensure smooth operation of your EFI.
“One component that is necessary to change or upgrade will be the use of a high-pressure electric fuel pump.” says Oberhelman. There is often some question about whether or not a relay should be used when installing the pump, and Oberhelman had a simple answer to that; “If you would like the pump to last forever and work right, a 12-volt relay will be a necessity.”
An electronic fuel pump is designed to push the fuel, not pull it, so you will be putting it near your gas tank. Since the tank is near the back of the car that means you are likely going to have to run a long wire from the front of the car back to the fuel pump. According to Oberhelman, “You will need a wire capable of carrying enough current to run your fuel pump. Due to the length of wire from a power source, I recommend a minimum of 12-gauge wire. Running that much current through your ignition switch isn’t recommended, because the switch will be overloaded, and decrease the voltage to the pump.” .
“The relay lets the ignition switch activate the fuel pump, while keeping the power from having to run through it,” Oberhelman told us. Running the electrical this way will keep constant power to the pump.
Here is a diagram that might help with relay installation:
- If your relay socket has a center pin, remove it
- Pin 30 receives fused 12-volt power from the battery
- Pin 87 goes to positive post of fuel pump
- Pin 86 goes to the orange wire from injection system
- Pin 85 goes to Ground
Along with the relay wiring information, FiTech provided us with some other basic tech tips for EFI installation:
- Make sure a quality, 100-micron prefilter is used between the fuel tank and the fuel pump.
- Keep the pump away from heat sources like exhaust.
- Electrical power to the fuel pump is key. You must run the correct wire size to it. And powering through a relay is preferred. You may be getting the proper voltage to it, but not the correct amperage. Remember: The longer the run of wire from the power source to the pump the more the power will drop.
Oberhelman also stressed the importance of proper grounding. If you don’t have a good ground, you don’t have a good fuel pump setup. “Many people will sand around the area where they make the connection, or even add a ground wire.” Oberhelman explained. “However, if they do not have a good ground from the body to the frame or engine, it will quickly kill their electric fuel pump.”
So just sanding for good contact is not enough. If you are trying to ground near the fuel tank, there is too much room for a poor body-to-frame ground. Oberhelman offers a simple solution: “The preferred method used by professional auto electricians is to run ground wires from a unit to a common grounding point,” Oberhelman detailed. “This is similar to grounding in a fiberglass car or boat.”
If you follow the guides that Oberhelman laid out for us, you should have no issues with your fuel pump setup. Make sure that if you are planning an EFI conversion, you bookmark this article for reference later. It could save you a lot of trouble in the long run.