Checking the Cold Start Valve and Thermo-Time Switch

PROCEDURE

K-Jetronic Fuel Injection System Diagram 1 – fuel tank; 2 – fuel filter; 3 – fuel accumulator; 4 – fuel pump; 5 – battery; 6 – ignition switch; 7 – fuel pump switch; 8 – ignition distributor; 9 – thermo-time switch; 10 – cold start valve; 11 – spark plug; 12 – injector; 13 – intake manifold; 14 – auxiliary air valve; 15 – throttle valve housing; 16 – throttle valve; 17 – air flow meter; 18 – air flow meter plate; 19 – plug; 20 – fuel distributor; 21 – warm-up regulator; 22 – fuel distributor plunger; 23 – pressure regulator; 24 – air flow meter plate lever; 25 – fuel distributor plunger control lever; 26 – mixture control screw (CO adjustment); 27 – mixture quantity adjustment screw

Cold start valve 10 is installed in the engine intake manifold. The valve supplies additional fuel into the intake manifold during cold engine starting. The valve is controlled by thermo-time switch 9. The thermo-time switch opens the valve during engine starting, depending on the coolant temperature. The higher the coolant temperature, the shorter the time the valve 10 stays open. If the temperature is high enough, valve 10 does not open. Check the valve and thermo-time switch on a cold engine, with coolant temperature below 30°C, as follows. PROCEDURE 1. Disconnect the wiring connector from valve 10. 2. Connect a test lamp between the connector terminals. 3. Remove the central high-tension lead from the ignition distributor and connect it to ground. 4. Disconnect the wiring connector from thermo-time switch 9.

5. Connect terminal 2 "W" (white-green wire) to ground with a jumper wire. Do not connect terminal 1 "G" (red-black wire) to ground. 6. Operate the starter; the test lamp should light. If the lamp does not light, there is an open circuit. 7. Unscrew the valve mounting bolts and carefully remove valve 10 so as not to damage the gaskets. 8. Reconnect the wiring connector to the valve, place a glass container under the valve, and operate the starter for 10 s. While the thermo-time switch is closed, the valve must spray fuel in a well-defined cone. Wipe the valve dry and check for fuel leakage. If no traces of fuel appear on the valve within 1 min, the valve is serviceable. Replace a faulty valve. 9. Disconnect the wiring connector from the valve and connect a test lamp between the connector terminals. 10. Operate the starter for 10 s. The lamp should light immediately and stay lit for 3 s.

If the lamp does not light, replace the thermo-time switch. 11. Install valve 10 in place and reconnect the wiring connector. 12. Reconnect the central high-tension lead to the ignition distributor.