Ok, I just bought a 1983 380 SEL and the engine would turn over, but wouldn't start. With all of my other Mercedes gassers, I would check the fuel pump, fuel filter,fuel relay, spark, disconnect fuel line to fuel distributor, loosen the lines at the top of the distributor to see if gas was getting through and other common problems when having starting problems. I used a jumper to see if the relay and pump are working and everything is good, but When pulling the relay, I noticed some wire disturbances where someone spliced in what is called a "k-loop" that I have no clue about.
There are also some wires that are cut and spliced and also the old wire that was cut was stuffed in between the hood spring in fuse box.
I don't know about the K loop, but there were four wires running to it out of the fuse box. One of the wires was red and look like it came from the fuel relay.when I looked closer the red wire that goes to the K loop was stuck inside the heat shrink protective casing along with the other three wires, but not connecting to anything. Here are some pictures to give you a better idea of this aftermarket mess. My goal is to get this car started and I have a feeling this K loop is the problem, because I have tried everything else.