In 1982 Alfa Romeo began to use the Bosch L-Jetronic fuel injection in the Spider. The system remained in use in the Spider until 1990. It was used in many other makes of cars and is extremely reliable. One notable weakness is vulnerability to ground fault problems. So make sure your ground points a making excellent contacts.
Another issue to keep on eye on in the case of the L-Jetronic in your Alfa is the soft fuel lines running from the tank forward and the short lines in the injector rail. These are basically nitrile rubber fuel lines and are now old and likely not served well by ethanol additives in modern fuel. The short lines on the injector rail are held in place by the tight fit of the rubber against the gallery and the injectors and little metal caps that keep the line at the fitting points from expanding. It seems impossible that they seal – but they do quite well.
While these soft fuel lines may look ok from the outside and ones in the rail are shiny and pristine looking, over time the interior degrades and cracks and they begin to weep fuel. It is typical to start seeing drops of fuel and then eventually you find small pools under the front of the fuel tank where the hoses attach. Remember that 1986-90’s Spiders have a fuel pump in the tank and will be pushing out fuel through any cracks in the soft line.
The soft fuel lines feed into an inline filter and then a second electronic pump underneath the car. By the way, if you usually run on a full tank and the the in tank pump fails, the external inline pump generally keep the engine running. The lines make their way to the a metal injector rail and then to the electronically controlled injectors on the cylinder head. When the short hoses to the injectors begin to fail you will see small amounts of wet fuel on the rail piping in the engine compartment. Take a look at your car immediately after running the engine and see if there is moisture from fuel on the metal rail.
The best thing to do is preempt any disaster and replace the softlines from the tank all the way up to the short injector hoses. Of course there is also a fuel return system and the soft hoses for that should be replaced at the same time. You will also want to replace the inline fuel filter. It is not a difficult job for the most part of you have a lift. The next article will show a few tricks.