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 Plymouth Horizon AutomaticFACTORY OEM SERVICE PROCEDURE
EFC System
- Description
- Operation
- Removal & Installation
- System Testing
- No Start Tests
- No Start Test 1 - Checking For Spark At Plug Wires
- No Start Test 2 - Checking For Fuel In Carburetor
- No Start Test 3 - Checking For Fuel Fouled Spark Plugs
- No Start Test 4 - Engine Timing Check
- No Start Test 5 - Ignition Coil Spark Check
- No Start Test 6 - Ignition Coil Primary Circuit Check
- No Start Test 7 - Fuel Pump Pressure Check
- DRIVEABILITY Tests
- Test 1 - Checking Diagnostic System For Fault Codes
- Test 2 - Oxygen Solenoid System Check
- Test 3 - Canister Purge Solenoid Control System Check
- Test 4 - Throttle Control Solenoid System Check
- Test 5 - V.O.S. Control Solenoid System Check
- Test 6 - Oxygen Feedback System Check
- Test 7 - Coolant Sensor Circuit Check
- Test 8 - Speed Sensor Circuit Check
- Test 9 - Checking For No Code 88
- Test 10 - Choke System Check
- Test 11 - Checking For Fuel Fouled Spark Plugs
- Test 12 - Bowl Vent System Check
- Test 13 - Carburetor Switch Check
- Test 14 - Coolant Sensor Calibration Check
- Test 15 - Choke System Check
- Test 16 - Carburetor Idle System Check
- Test 17 - EGR System Check
- Test 18 - Air Switching System Check
- Test 19 - Solenoid Kicker System Check
- Test 20 - Carburetor Bowl Vent System Check
- Test 21 - Computer Controlled Components Check
- Test 22 - Radiator Fan Relay Circuit Check
- Test 23 - Solenoid Kicker Operation Check
- Test 24 - Secondary Ignition System Check
- Test 25 - Basic Ignition Timing Check
- Test 26 - Engine Idle System
- Test 27
- Wiring Diagrams
Factory Service Tools
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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