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Home >> Mercedes Benz >> 1990 >> 560SEC >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Basic Testing >> Fuel System >> Visual Check (Fuel Leak)
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Visual Check (Fuel Leak)

  1. Remove air cleaner and check for any visible fuel leaks. Remove fuel pump relay from relay board (under hood on fuse panel). Bridge fuel pump relay board terminals No. 7 and 8 with jumper wire until fuel pressure is established.
  2. Push airflow sensor plate down manually. Uniform resistance should be felt throughout travel (after slight amount of free travel). No binding should be felt when sensor plate is released. If upward movement of sensor plate is slow, feel for resistance from control piston returning against sensor plate lever arm. No binding should be felt.
  3. Push airflow sensor plate completely down and briefly hold. No fuel should leak past control piston. Slight fuel seepage is acceptable. If no fuel leaks are found, go to next test.