Afternoon EFI

Afternoon EFI

Upgrading Your Carburetor Has Never Been Easier!

By Ryan Manson | Photography by the Author

When electronic fuel injection systems first showed up in the automotive aftermarket, they were complicated, bulky affairs. Installations were laborious, requiring high-pressure compliant fuel lines be run both to and from the gas tank, and in some situations a new tank altogether. Additional fuel filters and an external fuel pump were also required. A mounting location for the computer was required and with it an array of sensors and hardware that also needed to be installed. A wiring harness more complicated than the original vehicle’s main harness wasn’t uncommon, leading many to simply forego using this newfangled technology, leaving them stalwarts of the common carburetor.

FiTech Go Street EFI kit with a Force Fuel system laid out on a table

Here’s the FiTech Go Street EFI kit along with the Force Fuel system that we’ll be installing on the 1971 C10. You’ll notice that there isn’t a large ECU laid out amongst the parts. That’s because the ECU, as well as the 1-BAR MAP (manifold absolute pressure) sensor, IAC (idle air control) motor, TPS (throttle position sensor), and fuel injectors are all built into the throttle body. A handful of electrical connections and two sensors, the O2 and CTS (coolant temp sensor), are all that need to be installed. The handheld will be used for initial setup before we fire the engine for the first time.

The Force Fuel is basically a fuel sump designed to store a small amount of fuel (1/2 gallon) to ensure the fuel pump doesn’t cavitate or starve while boosting the stock fuel pressure to 58 psi (regulated internally) and delivering it to the injectors. Submerging the pump also keeps it cool, prolonging the pump’s life. The three connections at the top of the Force Fuel are the inlet from the stock mechanical fuel pump, the high-pressure outlet to the throttle body, and a return line that will go back to the tank. A direct-mount fuel pressure gauge makes it easy to ensure that the integrated pressure regulator is doing its job.

We’re using the mechanical fuel pump to feed fuel from the stock gas tank to the Force Fuel unit.

The Force Fuel kit came with a 10-micron fuel filter that we installed on the high-pressure side of the fuel system just before the throttle body.

But like all things technologically speaking progress happens, and before long what previously remained the domain of fuel injection specialists and computer programmers was repackaged, redesigned, and redeveloped to the point that an EFI installation today has almost become a plug-and-play situation. This ease of installation, coupled with self-learning capabilities, is what has propelled EFI’s popularity to the point that it’s likely to replace the carburetor as the go-to induction platform. Throttle body designs that mimic the traditional four-barrel carb make swapping one for the other a simple affair that doesn’t require an EFI-specific intake manifold like early tuned port injection setups. Advances in computers and electronics have allowed designs for the ECU to become so compact that many manufacturers are incorporating them into the throttle body themselves, making the installation that much simpler. And as the components become more mainstream, costs are driven down—to the point where an entry-level EFI kit is almost as affordable as setting up a new carbureted system.

bright orange Go Street EFI throttle body

Here’s the Go Street EFI throttle body atop the stock intake manifold on our 350 crate motor. It occupies roughly the same real estate as a standard four-barrel carburetor with similar attach points for the throttle and kickdown cable. Note the CTS installed in the front water jacket of the intake and connected to the throttle body’s wiring harness. The throttle body has three possible inlets: two in the front (currently plugged) and another at the driver side rear. A return line outlet is located at the passenger side rear after the internal pressure regulator. Since we will be installing a return line from the Force Fuel system, it’s not necessary to run another from the throttle body, so this will be plugged.

There are only a handful of electrical connections necessary for the Go Street EFI system. The ECU is set up to control the fuel pump, so it’s not necessary to route any wiring from the fuse panel for the pump. Instead, we’ll be connecting one side of this connector directly to the positive side of the battery and the other side will be connected to the positive terminal on the fuel pump.

The previous connector is mated to the harness on the right side of this image. The connector opposite has four wires and should be terminated as follows: blue to tach input signal, black to coil trigger, white to 12V switched during cranking, and yellow to ground terminal of electric fan relay. The ECU grounds through the throttle body and engine, so it’s important to have a good ground strap between the engine and the frame, or better yet, one directly to the battery.

We need to add a return line for the Force Fuel, but, unfortunately, our stock tank doesn’t have an extra port available for such. A new tank is not in the project’s budget and welding a bung in the tank is a bad idea. Luckily, CPP came up with a solution in their Universal Fuel Tank Return Line Bung kit. This crafty aluminum fitting acts like a rivnut once installed and makes adding a port to any tank easy. Here, the bolt is installed as the bung ships, but for installation, the AN-6 fitting is removed and the bolt installed from that end.

For a large portion of the truck market, retrofitting an original carbureted setup with an EFI system is the name of the game. That means swapping out the fuel tank and replacing all the existing fuel lines is out. Thankfully, companies like FiTech Fuel Injection have kits that are designed for such a situation. Utilizing the stock gas tank, fuel lines, and even the original, engine-mounted mechanical fuel pump is possible by using a sump-mounted EFI fuel pump, such as FiTech’s Force Fuel, that boosts the fuel pressure to an internally regulated 58 psi before sending the fuel onward to the injectors. For four-barrel V-8–equipped trucks, a simple swap of the carb with a FiTech throttle body, the installation of a few sensors, and a couple electrical connections are all that’s required to convert that old hauler to modern, reliable fuel injection.

Recently, while this 1971 Chevy C10 was getting a head-to-toe once-over, as the drivetrain was being buttoned up, the owner decided he wanted to make the upgrade to an EFI system. The original gas tank and fuel lines would remain, as he wanted the installation to look as original as possible while being friendly on the pocketbook. That led to the decision of going with FiTech’s Force Fuel unit along with their Go Street EFI system. Designed as a direct replacement for standard four-barrel carburetors, the Go Street EFI system is a perfect balance of complexity in its capabilities and simplicity in its form and function. The ready-to-run system sticks to the basic functions necessary to achieve the best performance and economy possible with very little input required from the end user. No specialized knowledge or tuning required, the Go Street EFI system is about as plug-and-play as fuel injection comes and is the perfect fit for this project—and quite possibly, yours as well!

To install the bung, a 1/2-inch hole is first drilled in the tank near the top. The bung is then installed flush with the surface of the tank. The bolt is then installed in place of the AN-6 fitting and drawn tight while holding the bung with a separate wrench. Once tight, the end of the bung inside the tank deforms, drawing tight against the inside wall of the gas tank, securing the bung in place.

Installing the O2 sensor is just as easy, with no welding required. Just behind either collector, toward the top, a 7/8-inch hole is drilled to accept the sensor. The sensor bung and gasket are then clamped in place over the hole and the O2 sensor installed.

The handheld controller provided with the Go Street EFI kit is a handy, informational piece of kit, but for now, we’re only concerned with accessing the “Go-EFI Initial Setup” menu.

Then, it’s a simple matter of entering our particular parameters before we can crank the motor and, finger’s crossed, light the fire. Once up and running, the ECU will use the information from the sensors to determine the exact fuel requirements of the engine at any given second, automatically creating a detailed fuel map specific to that vehicle, all without the driver being any the wiser.

With an open afternoon, we set out to upgrade the base model 350ci crate motor with fuel injection. The fuel system was already plumbed from the stock gas tank to the mechanical fuel pump on the engine, and once a mounting location for the Force Fuel was arranged, the plumbing was continued from the stock pump to it. The throttle body was then installed, followed by the final section of fuel line. The Force Fuel unit does require a return line, which we ran back to the tank and used a Universal Fuel Tank Return Line Bung kit to access the stock tank. The Go Street EFI kit uses a single O2 sensor, which we installed in the passenger side exhaust using the provided sensor and installation kit. From there, it was a simple matter of making a few electrical connections, attaching the throttle and kickdown cables, and entering a couple parameters into the FiTech handheld before we were ready to crank and fire. Follow along and you’ll see how truly easy it is to go from carbureted to injected in an afternoon.

Sources:

FiTech Fuel Injection

(951) 340-2624
www.fitechefi.com

Classic Performance Products (CPP)

(800) 522-5004
www.classicperform.com

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