Cold Start Valve (420 & 560 Series) Test

With ignition off, disconnect coolant temperature sensor. Unplug Green cable on ignition switching unit (located on firewall). Crank engine and check voltage at plug of cold start valve. Voltage should be 10 volts for about 9 seconds. If okay, test is complete. If 10 volts are not read, go to next step.
Check wire from cold start valve to fuel pump relay and ground wire to engine for continuity. Resistance should be zero ohms. If resistance is not about zero ohms, repair open circuit and go to next step. If okay, test is complete.
With coolant temperature sensor disconnected, check voltage between fuel pump relay connector terminal and engine ground (-). Check terminal No. 2 and engine ground (-). Crank engine (do not start). Voltage at fuel pump relay connector should be 10 volts. Voltage at terminal No. 2 should be 3.5-5.0 volts. If not to specification, repair wiring circuits. If okay, replace fuel pump relay.