Fuel Injection Trouble Shooting

2025 Ford Escape ST-Line HybridSECTION Fuel Injection Trouble Shooting
NOTE: This is GENERAL  information. This article is not intended to be specific to any unique situation or individual vehicle configuration. The purpose of this Trouble Shooting information is to provide a list of common causes to problem symptoms. For model-specific Trouble Shooting, refer to SUBJECT, DIAGNOSTIC, or TESTING articles available in the section(s) you are accessing.
BASIC FUEL INJECTION TROUBLE SHOOTING CHART

CONDITION & POSSIBLE CAUSE CORRECTION
Engine Won't Start (Cranks Normally)
Cold start valve inoperative Test valve and circuit
Poor connection;vacuum or wiring Check vacuum and electrical connections
Contaminated fuel Test fuel for water or alcohol
Defective fuel pump relay or circuit Test relay and wiring
Battery too low Charge and test battery
Low fuel pressure Test pressure regulator and fuel pump, check for restricted lines and filters
No distributor reference pulses Repair ignition system as necessary
Open coolant temperature sensor circuit Test sensor and wiring
Shorted W.O.T. switch in T.P.S. Disconnect W.O.T. switch, engine should start
Defective ECM Replace ECM
Fuel tank residual pressure valve leaks Test for fuel pressure drop after shut down
Hard Starting
Disconnected hot air tube to air cleaner Reconnect tube and test control valve
Defective Idle Air Control (IAC) valve Test valve operation and circuit
Shorted, open or misadjusted T.P.S. Test and adjust or replace T.P.S.
EGR valve open Test EGR valve and control circuit
Poor Oxygen sensor signal Test for shorted or circuit
Incorrect mixture from PCV system Test PCV for flow, check sealing of oil filter cap
Poor High Speed Operation
Low fuel pump volume Faulty pump or restricted fuel lines or filters
Poor MAP sensor signal Test MAP sensor, vacuum hose and wiring
Poor Oxygen sensor signal Test for shorted or open sensor or circuit
Open coolant temperature sensor circuit Test sensor and wiring
Faulty ignition operation Check wires for cracks or poor con- nections, test secondary voltage with oscilloscope
Contaminated fuel Test fuel for water or alcohol
Intermittent ECM ground Test ECM ground connection for resistance
Restricted air cleaner Replace air cleaner
Restricted exhaust system Test for exhaust manifold back pressure
Poor MAF sensor signal Check leakage between sensor and manifold
Poor VSS signal If tester for ALCL hook-up is available check that VSS reading matches speedometer
Ping or Knock on Acceleration
Poor Knock sensor signal Test for shorted or open sensor or circuit
Poor Baro sensor signal Test for shorted or open sensor or circuit
Improper ignition timing See VEHICLE EMISSION CONTROL LABEL (where applicable)
Check for engine overheating problems Low coolant, loose belts or electric cooling fan inoperative
NOTE: For additional electronic fuel injection trouble shooting information, see the appropriate article in the ENGINE PERFORMANCE section (not all vehicles have Computer Engine Control articles). Information is provided there for diagnosing fuel system problems on vehicles with electronic fuel injection.
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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.