The fuel is cold when you start the engine, even if the block heater is plugged in, the fuel in the lines and tank are going to be cold until the engine is up to temp. So if the fuel can get too cold to flow or whatever, how is the engine supposed to run until its warm enough to heat the fuel?

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1985 300TD-euro 352,000 mi
1974 240D (1?)52,000 mi - has a new home now