Full Throttle Enrichment Switch, Checking

Checking Full Throttle Switch

Note: Full throttle switch supplies the control unit with information to increase amount of fuel injected at full throttle

CAUTION: Do not connect test light to throttle valve switch connectors if control unit is connected





First Check, Throttle Valve Switch

- Disconnect throttle valve switch connectors
- Attach ohmmeter to switch 3
Throttle valve closed; switch turned OFF = infinite ohms
Throttle valve full open; switch turned ON = 0 ohms

Second Check, Wiring And Control Unit

- Run engine at idle for a short time
- Stop engine and turn ignition ON
- Pull off connectors from both throttle valve switches
- Check voltage between connectors of full throttle enrichment switch
Voltage should be approx. 5 volts
If NO, control unit is defective or break in wiring

Third Check, Full Throttle Enrichment

Test conditions:
Result of first and second check must be OK
Throttle valve switch connectors connected
Temperature at temperature sensor II must be minimum 60°C (140°F) and resistance below 550 ohms
CO tester and tachometer connected

Work Procedure:
- Run engine for about 2 minutes at idle speed
- Increase idle speed slowly until tachometer reads about 4000 rpm
CO should be between 0.3 to 1.1%

- With engine at about 4000 rpm, operate full throttle enrichment switch 3 by hand for about 15 seconds
C0 must increase above 1.5%
If NO, control unit is defective