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SPN 1347 FMI 5

Engine Fuel Pump Pressurizing Assembly #1 — Current below normal or open circuit.
Less current is flowing in an output or sensor circuit than expected, which usually means the circuit is open.

What the SPN covers: The electronically controlled valve or actuator on the high-pressure pump — often called the fuel pump actuator, inlet metering valve or FCA — that sets how much fuel the pump sends to the rail. More on SPN 1347.

What FMI 5 usually points to: Broken wire, unplugged connector, burned-out coil or solenoid, or a backed-out terminal. More on FMI 5.

Severity

HIGH — limit use, diagnose now

If the computer cannot control the pump, rail pressure goes low or erratic and the engine may derate, stall or not start.

Likely causes

  1. Wiring or connector fault in this circuit (most common for electrical FMIs)
  2. Actuator coil open or shorted
  3. Damaged harness or corroded connector
  4. Valve sticking from debris, water or varnish in the fuel
  5. Low supply pressure forcing the valve to its limit

Checks & fixes (easiest first)

  1. Inspect the connector and harness for this circuit: corrosion, water, chafing, backed-out pins
  2. Check the reference voltage, ground and signal at the component per OEM pin-out
  3. Inspect the actuator connector and measure coil resistance
  4. Compare commanded actuator current with desired vs. actual rail pressure
  5. Check fuel supply pressure and filters before blaming the valve
  6. Look for debris or water in the filters — contamination may have hurt the pump too

Troubleshooting guides

FAQ

What does SPN 1347 FMI 5 mean?

Engine Fuel Pump Pressurizing Assembly #1 — current below normal or open circuit. Less current is flowing in an output or sensor circuit than expected, which usually means the circuit is open.

Is SPN 1347 FMI 5 serious?

If the computer cannot control the pump, rail pressure goes low or erratic and the engine may derate, stall or not start.

What should I check first for SPN 1347 FMI 5?

Inspect the connector and harness for this circuit: corrosion, water, chafing, backed-out pins; Check the reference voltage, ground and signal at the component per OEM pin-out; Inspect the actuator connector and measure coil resistance.