The Pros And Cons Of Swapping A Carburetor For Fuel Injection

Electronic fuel injection revolutionized the auto industry in the 1980s. It came to replace the carburetor in the task of sending fuel to the engine's cylinders but it does much more: it controls several parameters of the engine's operation, can alter those parameters in an instant, and logs all those changes for future reviews. As a result, it took automotive engines to a whole other level — they became more powerful, more efficient and less pollutant all at once.

Then again, none of that means that the carburetor should be forgotten. The industry used it for decades in many kinds of machines, including motorcycles and generators, and made sure to improve it over that time. Carburetors were phased out mostly because stricter emissions regulations eventually made it easier to switch to fuel injection altogether. When it comes to enthusiast use, typically among classic and racing cars, swapping a carburetor for fuel injection remains a rich and valid debate.

In short, electronic fuel injection is better for its overall efficiency: it makes the engine run in optimal conditions at all times, which leads to several significant benefits. On the other hand, installing that system in a car that wasn't built for it requires replacing many parts and working a lot to make everything work safely and reliably.

In modern systems, the electronic control unit feeds the fuel injection system with data such as throttle position, air intake, and engine load. Then the fuel injection uses that information to determine other data, like air/fuel ratio and ignition timing. That teamwork is updated in real time to keep the engine away from operating ranges that would increase fuel consumption and/or tailpipe emissions.

The carburetor relies on purely mechanical resources: the main ones are a throttle valve to regulate airflow, a float chamber from which fuel is drawn through jets, and a tube with a narrowing section where air meets fuel in a controlled way. In normal conditions, it can adapt to how much the gas pedal is pressed and not much else. There's a choke valve to help with cold starts, but it does so by adding more fuel than usual to the air/fuel mixture, which increases consumption.

Besides the technical gains already mentioned, there are others: fuel injection systems idle more smoothly, start more easily on cold mornings, and are easier to diagnose with scan tools. They are also less prone to fuel leaks, and require less frequent maintenance, since carburetors need periodic tuning and balancing. Besides being more efficient, modern fuel injection systems offer more consistent performance, which helps explain why they eventually dominated the mass market.

While the industry has largely moved past the carburetor — especially in five-cylinder engines — it still has significant advantages. The most intuitive ones are related to its simplicity: having few components makes it easy to repair and even to upgrade with a turbo. There's also a huge cost difference: while a carburetor set costs around $450, a fuel injection set can reach approximately four times as much, both before shipping (if applicable) and labor costs.

And the operation's complexity overshadows its potential benefits. Fuel-injected cars are more sensitive to dirty fuel and varying pressure, so they need more precision from the fuel system — think of adding fuel filters before and after the fuel pump, a fuel pump that can flow at least 67 gallons per hour and, in most cases, a return line from the engine to the tank. It's also important to upgrade the wiring system to adequately ground the chassis and engine block to the battery and prevent too many fuses and/or messy wiring. Ignition and fuel injector upgrades may be necessary as well.

In the end, while fuel injection is great in many ways, the truth is that the carburetor is far from dead — in fact, it equipped new cars in North America up to the 1990s. Installing fuel injection in a carbureted car implies an extensive and detailed operation, though you might be able to do it yourself. The task won't be quick, of course, but some modern systems offer plug-and-play installation to make it less difficult. Regardless of the system you choose, it's advisable to find reliable suppliers, do your research, and take your time with that conversion.