The early L-Jet Spiders did not have an altitude compensator. Rather, a jumper was to be dealer installed if the vehicle was to be operated at altitudes above 1000 meters or so. Later L-Jets did have an altitude compensator. The change over occurred in or for the 1984 model year. To determine if your Spider came with, or needs, an altitude compensator, look at the last three digits of the Bosch part number on the fuel ECU.
206 = no compensator (jumper if required)
221 = compensator equipped
I know where it's supposed to be, but therein lies the problem, it's not there! Do I have to have it? Since I live in Cleveland, Ohio, I don't think I need it. Do I have to do something to make it run right without one?
I would think that with a missing, or failed, compensator, that the ECU would use a fixed value for the altitude. Meaning that the engine would run. But I don't know this for certain.
I should have a good used compensator. I'll have a look and get back to you...