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Troubleshooting Teleflex Oil Pressure Gauges - Inboard & Stern Drive

Technical Reference Manual

Oil Pressure System- Inboard & Stern Drive

  1. To test the gauge, voltage from "I" to "G" terminal must be 10-16 volts DC, with no wire on "S" terminal. Gauge pointer should rest below the "0 PSI" mark. Next, connect the "S" terminal to the "G" terminal (leave "I" and "G" terminals connected). The gauge pointer should rest above the maximum pressure mark.
  2. Sender resistance can be measured to determine the sender's correct operation. Remove wire to gauge. Connect an ohmmeter to terminal of sender and to engine block. Approximate pressure sender resistance values are:
    • Zero pressure = 240 ohms
    • 1/2 gauge reading = 103 ohms
    • full gauge pressure = 33 ohms.
    • You will get half these values on a dual gauge sender.
  3. If sender is shorted (0 ohms) gauge will read above full gauge pressure reading.
  4. If sender has infinite resistance (open) gauge will read below 0 PSI.
  5. If gauge reads lower than expected, was sealer used on the sender threads? (See illustration.)
  6. The accuracy of the system (gauge & sender) can be 5 PSI at 40 or 50 PSI.
  7. Use of pipe extenders to plumb both a sender and pressure switch (for horn or warning light) from one port is not recommended. Pressure readings will be accurate, but the weight added to the extended fitting of a vibrating engine may cause fatigue related break age.
  8. Teleflex does not offer senders for metric threaded ports.
  9. Dual Station installations:
    1. When replacing one gauge in a two station installation, the second gauge may need to be replaced as well.
    2. Mixing two gauges from different manufacturers to one sender may cause an error in both gauges.
    3. If one gauge fails the second gauge will read much higher than expected.
    4. If sender fails "open", both gauges will read below the "0" mark.
    5. If sender fails "short", both gauges will read above the "full pressure" mark.
  10. Twin engines: it may be helpful in troubleshooting to switch either the senders or the gauges from engine to engine.

Oil Pressure Sender I.D. Guide

Use this chart for field identification of Teleflex pressure senders. (ID code stamped on wrench hex of sender. See illustration below chart.)

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