By the mid 1960s, mechanical fuel injection had been successfully employed in Formula One and sports car endurance racing for more than a decade. But manufacturers were just beginning to install it on production cars. Volkswagen introduced it first in 1967 on what the company referred to as the Type 3: the notchback, squareback, and fastback models. It was a Bosch system called D-Jetronic. Volkswagen would not introduce fuel injection to the rest of its line-up until 1975, when they switched to the Bosch L-Jetronic system for their Beetle, Super Beetle, and Type 2, better known as the Bus.
Bosch had developed a direct injection system for gasoline engines as early as 1952, for the Goliath GP 700, a misnomer if there ever was one. The Goliath was a tiny car only 160 inches long, and production numbers were low. The VW Type 3 was the first production model built in sizable numbers to sport mechanical fuel injection on gasoline engines.
These were simple systems, but all systems break down over time. And forty years is a pretty long time. Today, parts are increasingly difficult to find, especially for the earliest D-Jetronic system. Even finding mechanics experienced with these early systems can be a challenge. Some owners prefer to go the DIY route. And some convert their engines to carburetion instead. There are useful manuals out there for the DIY-ers. One that is a little pricey but very helpful is Bosch Fuel Injection and Engine Management, by Charles O. Probst.
Several aftermarket companies make replacement “bolt on” fuel injection systems, but installation is typically far more complicated than merely bolting them on. They may require some drilling, fuel line modification, and perhaps welding of the O2 sensor. You have to be a pretty ambitious DIYer to tackle this job. And the initial cost of these systems can also be prohibitive. Some of these do come in kits, however, which help to simplify the process. For the truly ambitious DIYer, you can always build a system from scratch. But that will involve not only the new fuel line, but also the pressure regulator, electric pump, throttle body and its sensor, a computer, and of course, the injectors. And anyone ambitious enough to consider going this route has probably already replaced the Bosch system.
There are many paths you can take to put your VW back on the road, some far more elaborate than others. A lot of it is simply deciding what is best for you, your car, and your pocket book.