Throttle Position Sensor: Adjustments

NOTE: Before testing the TPS, the throttle linkage must be checked for correct adjustment. The throttle lever must do the following:

^ Contact the low idle speed screw
^ Reach breakover when the throttle is wide open.

If the throttle lever does not meet both of the previous conditions, adjust the throttle linkage.

Throttle Position Sensor Adjustment:

NOTE: A digital voltmeter is required in order to be able to adjust the throttle position sensor.

1. Connect the negative lead of the voltmeter to the negative terminal of the battery, or a good ground location.
2. Using a sharpened paper clip, back probe the center electrical terminal of the TPS electrical connector. Connect the positive lead of the voltmeter to the paper clip that is back probing the TPS electrical connector.

Throttle Lever And Low Idle Speed Screw:

Throttle Position Sensor Adjustment:

3. Turn the ignition switch to the ON position, and verify that the injection pump throttle lever is contacting the low idle speed screw.
4. The TPS output voltage, when the throttle shaft is at idle position, should be 1 volt. If the output voltage is not at the specification, use an open end wrench and adjust the TPS sensor shaft until a 1 volt output is achieved. The TPS sensor shaft is machined to accept an open end wrench for adjustment.

Breakover Spring Position:

5. Open the throttle to the wide open throttle position, the spring load breakover lever should have moved off the stop and rest against the breakover spring. If the previous condition does not occur, the throttle actuation rod needs to be adjusted before the TPS is adjusted.
If the throttle actuation rod needs no adjustment, go to step 6.
6. With the throttle held in the wide open throttle position, check the TPS output voltage. It should be at least 3.25 volts. If the output voltage is not at least 3.25 volts, adjust the TPS sensor shaft with an open end wrench.