Home › Codes › SPN 1347 › FMI 3

SPN 1347 FMI 3

Engine Fuel Pump Pressurizing Assembly #1 — Voltage above normal or shorted high.
The sensor circuit voltage is higher than it should ever be, usually pegged near the supply voltage.

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 3 usually points to: Signal wire shorted to the 5 V reference or battery, an open ground, or an unplugged sensor on a pulled-up circuit. More on FMI 3.

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 3 mean?

Engine Fuel Pump Pressurizing Assembly #1 — voltage above normal or shorted high. The sensor circuit voltage is higher than it should ever be, usually pegged near the supply voltage.

Is SPN 1347 FMI 3 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 3?

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.