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Mercedes SL380 1981

Car is driven seldom. Less than 1000 mpy. Initially it will start on first turn of key. After driving for an hour or so and then letting the car sit and cool down for an hour or so it is very difficult to start. It seems as if pumping the gas finally works but not sure this is making it start or just constantly turning it over is the reason. Any suggestions? One individual thinks it’s ignition wires that are carbonized and need to be replaced???

Try your question here:

Spark plug wires from cars of this era were often carbon impregnated to reduce radio interference. These wires are very sensitive to mishandling and can break down internally. If you replace them with current, or copper core plug wires, you might need a “resistor” in the radio to reduce radio interference from the new wires.

If you simply lean on carbon impregnated wires that can make them deteriorate. Had them on several cars in the '60’s and '70’s and eventually was glad when they went out of style.

This car has CIS injection and running fuel pressure tests are the first step in diagnosing a performance problem with CIS. This requires a specialized fuel pressure tester and knowledge of how the system works so you would need a Benz, VW, BMW, or Volvo guy who is famliar with this setup.

Fuel injectors that bleed off are a very common problem with CIS and cause a flooded condition. This could explain the hard start when warm and depressing the pedal helping.

my 2cent vote is clogged fuel filter, or sticky something that has to do with fuel distribution