Hard to Start

Definition: Engine cranks OK, but does not start for a long time. Does eventually run, or may start but immediately dies.
- CHECK:
- For water contaminated fuel.
- Fuel pressure. See CHART A-6. Chart A-6 Fuel System Pressure Test
- TPS for sticking or binding.
- EGR operation.
- Fuel pump relay - Connect test light between fuel pump connector CKT 120 and ground. Light should be "ON," for 2 seconds, following ignition "ON".
For single tank system see CHART A-5. Chart A-5 Fuel Pump Relay Circuit Diagnosis (One Fuel Tank)
For dual tank system see CHART A-5A. Chart A-5A Fuel Pump Relay Circuit Diagnosis (Two Fuel Tanks)
On 7.4L, and some 5.7L engines, a fuel module circuit will run the fuel pump for 20 seconds, following ignition "QN". If this circuit is not functioning, this may cause a hot, hard start condition. See CHART A-5 or A-5A.
- For a faulty in-tank fuel pump, check valve, which would allow the fuel in the lines to drain back to the tank after the engine is stopped. To check for this condition:
1. Ignition "OFF."
2. Disconnect fuel line at the filter.
3. Remove the tank filler cap.
4. Connect a radiator test pump to the line and apply 103 kPa (15 psi) pressure. If the pressure will hold for 60 seconds, the check valve is OK.
- Long cranking time but eventually runs. Refer to CHART A-3, "Engine Cranks But Will Not Run." Related Tests, Information and Procedures
- Check ignition system for:
- Proper output, with J 26792 (ST-125).
- Worn shaft.
- Bare and shorted wires.
- Pickup coil resistance and connections.
- Loose ignition coil ground.
- Moisture in distributor cap.
- Spark plugs, wet plugs, cracks, wear, improper gap, burned electrodes, or heavy deposits.
- If engine starts, but then immediately stalls, open distributor bypass line. If engine then starts, and runs OK, replace distributor pickup coil.
- Hard start, with engine at normal operating temperature. See Crank Signal Diagnosis. Chart C-1B Crank Signal Diagnosis
- Check CKT 423 (EST) for short to ground.