Hard Start or Long Crank — 6.7 Cummins (EGR + DPF, pre-SCR)
A diagnostic guide for hard start or long crank on 6.7 Cummins (EGR + DPF, pre-SCR) 2007.5–2012.
What’s going on
On this engine a long crank is usually low fuel rail pressure from supply problems, air in the fuel or a fuel control actuator fault, or — in the cold — an intake air grid heater that is not working.1
Most likely causes
- Low fuel supply pressure from the in-tank lift pump, clogged filters or air ingress causing low rail pressure — Insufficient low-side pressure reduces CP3 inlet flow, leading to slow rail pressure build and extended cranking. This commonly sets P008A for low-pressure fuel system pressure too low and can contribute to P0087 rail pressure too low.123
- Fuel control actuator (FCA/MProp) performance or circuit fault — A sticking or electrically faulty FCA limits CP3 pressure control, causing slow rail pressure rise on start. This can set P0090 for fuel pressure regulator control circuit and P0087 for rail pressure too low.143
- Air in fuel or leak on the low-pressure side — Air ingestion prevents rapid rail pressure build, producing long crank and often rail-pressure codes. Typical with supply-side leaks, filter housing issues or lift-pump problems.13
- Intake air grid heater system not performing — Cold-start combustion is degraded when the grid heater does not heat intake air. The 6.7L uses a grid heater, not glow plugs, and a non-performing heater can set P2609 and cause hard cold starts.156
How to narrow it down
- Read stored trouble codes and freeze frame; note P0087, P008A, P0090, P2609 if present.
- Check battery voltage and cranking speed; verify base electrical health before fuel tests.
- Inspect low-pressure supply: measure lift-pump output volume/pressure at the filter housing per service spec; check for air bubbles in the clear supply line and inspect filter housing, seals and connections for leaks.
- Inspect fuel control actuator electrical connector and wiring for corrosion or damage; check FCA command vs rail pressure during cranking with a scan tool.
- Check intake air grid heater operation in cold conditions: verify relay activation, heavy cable integrity and heater element resistance; confirm P2609 conditions and battery voltage during heater run.
- If rail pressure is slow to build, perform a controlled leak-down and supply-side isolation to separate lift-pump/air-ingress issues from FCA/rail-pressure control issues.
Specs and test values
| Check | Normal reading | When to measure | Source |
|---|---|---|---|
| Battery and charging voltage | 12.6–12.7 V at rest when fully charged; about 13.5 V running | Engine off, then running with loads on | DieselHub |
Parts and tools you may need
- Scan tool with live rail pressure and FCA command
- Fuel pressure gauge for low-side supply test
- Clear fuel line or inspection hose for air bubble check
- Multimeter for grid heater relay and element resistance
- Service manual pressure/volume specs for in-tank lift pump
Tools you’ll need
- OBD-II scan tool with live data — Reads P0087/P008A/P0090/P2609 and shows rail pressure vs FCA command during cranking to isolate supply vs control faults.
- Digital multimeter — Checks battery voltage, grid heater relay activation, heater element resistance, and FCA circuit integrity.
- Fuel pressure test kit with low-pressure gauge — Measures lift-pump output volume/pressure at the filter housing and detects air ingress on the low-pressure side.
- Clear fuel supply line or inspection hose — Allows visual detection of air bubbles in the low-pressure supply during cranking and priming.
Rough cost and difficulty
| Likely repair | Parts | Shop labor | Who usually does it |
|---|---|---|---|
| Intake grid heater relay | $40–$150 | 0.5–1 hrs | Easy DIY |
| Fuel supply or return line repair | $30–$200 | 0.5–2 hrs | DIY with tools and a manual |
| Fuel pressure control valve (FCA/regulator) | $100–$400 | 0.5–2 hrs | DIY with tools and a manual |
| Lift pump / fuel transfer pump | $100–$400 | 1–3 hrs | DIY with tools and a manual |
Typical US independent-shop figures; labor runs about $120–$180 per hour (dealers charge more). Confirm the diagnosis before buying parts.
When to see a pro
If high-pressure fuel system testing is required or internal CP3/rail issues are suspected, have a qualified diesel technician perform diagnosis. Do not service high-pressure fuel components without proper training and safety equipment.
Check for recalls
Recalls are tied to your truck’s VIN, so check yours directly: enter the VIN at NHTSA’s recall lookup. Open safety recalls are repaired free at a dealer.
Related trouble codes
- P0087 — Fuel Rail/System Pressure Too Low
- P008A — Low Pressure Fuel System Pressure Too Low
- P0090 — Fuel Pressure Regulator Control Circuit
- P2609 — Intake Air Heater System Performance
Sources
Curated symptom seed — 6.7 Cummins (EGR + DPF, pre-SCR) (curated) ↩︎ ↩︎ ↩︎ ↩︎ ↩︎
Curated DTC seed — 6.7 Cummins (EGR + DPF, pre-SCR) (curated) ↩︎
Curated symptom seed — 6.7 Cummins (EGR + DPF, pre-SCR) (curated) ↩︎ ↩︎ ↩︎
Curated DTC seed — 6.7 Cummins (EGR + DPF, pre-SCR) (curated) ↩︎
Curated DTC seed — 6.7 Cummins (EGR + DPF, pre-SCR) (curated) ↩︎
Curated symptom seed — 6.7 Cummins (EGR + DPF, pre-SCR) (curated) ↩︎
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