What year and model? No that does not sound normal. You can check for full travel by pushing the pedal all the way down and seeing if the linkage on the injection pump is hitting the limiter screw.

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1979 240D- 316K miles - VGT Turbo, Intercooler, Stick Shift, Many Other Mods - Daily Driver

1982 300SD - 232K miles - Wife's Daily Driver

1986 560SL - Wife's red speed machine