SPN 94 — Fuel Delivery Pressure
System: Fuel
Low-pressure fuel supply pressure feeding the high-pressure pump, after the lift pump and filters.
Can I keep running it?
HIGH — limit use, diagnose now
Low fuel supply can cause power loss, hard starting and pump damage. Address before working the engine hard.
Likely causes
- Clogged fuel filter(s)
- Failed or weak lift/transfer pump
- Air leak on the suction side
- Low fuel level or gelled fuel in cold weather
- Faulty pressure sensor
Checks & fixes (easiest first)
- Replace fuel filters and prime the system
- Check for air in clear lines or a sight glass
- Measure supply pressure with a mechanical gauge
- Check tank pickup and vent
Common FMIs with SPN 94
- SPN 94 FMI 1Value too low (most severe)
- SPN 94 FMI 3Voltage above normal or shorted high
- SPN 94 FMI 4Voltage below normal or shorted low
- SPN 94 FMI 17Value too low (least severe)
- SPN 94 FMI 18Value too low (moderately severe)
Related codes
FAQ
What does SPN 94 mean?
SPN 94 is Fuel Delivery Pressure. Low-pressure fuel supply pressure feeding the high-pressure pump, after the lift pump and filters.
Can I keep running with SPN 94?
Low fuel supply can cause power loss, hard starting and pump damage. Address before working the engine hard.
What causes SPN 94?
Clogged fuel filter(s); Failed or weak lift/transfer pump; Air leak on the suction side; Low fuel level or gelled fuel in cold weather; Faulty pressure sensor.