Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
1987 Mercedes Benz 300EFACTORY OEM SERVICE PROCEDURE
Cold Start Injector
- Disconnect cold start injector. Connect multimeter to cold start injector connector. Remove ignition distributor transmitter plug from switching unit (Green cable) or install Protective Plug (102 589 02 21 00 ) on diagnostic socket.
- Check voltage while cranking starter motor. Reading should be at least 10 volts. Disconnect fuel line on cold start injector. Remove injector and reconnect fuel line. Hold cold start valve into container.
- Disconnect electrical plug at thermo time switch. Connect terminal "W" on plug to ground with jumper wire. Below 45Β°F (5Β°C), it is not necessary to ground thermo time switch connector. Start engine. Fuel spray from cold start injector should be cone shaped. Disconnect ground test lead if used.
- Dry any gasoline from nozzle of cold start valve. No droplets should form. Remove jumper wire. Install injector with new gasket. Reconnect wiring. Install relay and reconnect fuel line.
NOTE:
During warm-up and at operating temperature, current to differential pressure regulator is determined by coolant temperature sensor, O2 sensor and ECU.
Factory Service Tools
Use the Manual With the Right Hardware
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- β’ You smell fuel, burning insulation, or see smoke.
- β’ Brakes feel soft, pull hard to one side, or make grinding noises.
- β’ The engine overheats, stalls repeatedly, or misfires under load.
- β’ You are missing required tools, torque specs, or safe lifting equipment.
- β’ You are not confident in the next step or safety outcome.
