SPN 94 FMI 1 — Fuel Delivery Pressure — Low
What it means: Low-side fuel delivery pressure is below the expected range.
How serious / can you keep driving: Serious. Limp to the next safe stop.
Check first: Check and, if due, change the fuel filters — restriction here is the most common cause.
Don't risk it — look up listed providers near you and give them this SPN/FMI when you call.
Listed providers nearest Sparks, NV
Closest first. Tell them SPN 94 FMI 1 and what the truck is doing. RoadService.app lists these providers and does not employ them or carry out the repair.
- 0.0 mi away — based in Sparks, NV · (775) 355-6884
- 0.0 mi away — based in Sparks, NV · (775) 356-7200
- 0.0 mi away — based in Sparks, NV · (775) 359-0550
What SPN 94 FMI 1 means
Low-side fuel delivery pressure is below the expected range. The engine can lose power, surge, or stall, and a hard low-pressure condition can prevent starting. Most often it's fuel supply restriction rather than the high-pressure pump.
How serious is it?
Serious. Limp to the next safe stop.
Most likely causes
- Plugged fuel filters (the #1 cause) or a restricted supply line
- Air in the fuel system (loose fitting, cracked line, bad o-ring)
- Weak lift/transfer pump
- Gelled fuel in cold weather or a clogged tank screen
First moves (roadside)
- Check and, if due, change the fuel filters — restriction here is the most common cause.
- Look for air leaks on the suction side: loose fittings, cracked lines, weeping o-rings.
- In cold weather, suspect gelled fuel — treat/thaw before condemning the pump.
- Compare actual vs desired rail/supply pressure in the data before replacing parts.
Common misdiagnoses
- Condemning the high-pressure pump when plugged filters were starving it.
- Missing an air leak on the suction side that mimics a weak pump.
- Overlooking gelled fuel as the cold-weather culprit.
FAQ
Low-side fuel delivery pressure is below the expected range. The engine can lose power, surge, or stall, and a hard low-pressure condition can prevent starting. Most often it's fuel supply restriction rather than the high-pressure pump.
Serious — Limp to the next safe stop.
The most common cause is: Plugged fuel filters (the #1 cause) or a restricted supply line. Other possibilities include Air in the fuel system (loose fitting, cracked line, bad o-ring); Weak lift/transfer pump; Gelled fuel in cold weather or a clogged tank screen.
Limp to the next safe stop. When in doubt, get a qualified mobile diesel tech on the truck before continuing.
Related codes
Codes that commonly appear alongside SPN 94 FMI 1, or share the same subsystem.
- Injector Metering Rail 1 Pressure - Data Valid But Below Normal Operating Range (XPI common rail fuel pressure too low) (SPN 157 FMI 1)
- Injection Rail Pressure — Below Normal (SPN 157 FMI 18)
- Injector Metering Rail 1 Pressure - Data Valid But Above Normal Operating Range (XPI common rail fuel pressure too high) (SPN 157 FMI 0)
- Injector #1 open circuit (SPN 651 FMI 5)
- Injector #2 open circuit (SPN 652 FMI 5)
- Injector #3 open circuit (SPN 653 FMI 5)
- Injector #4 open circuit (SPN 654 FMI 5)
- Injector #5 open circuit (SPN 655 FMI 5)
Same symptom: Fuel delivery
Other codes on the tank-to-injector path — pressure, filters, water and the pump.
- Fuel System Leak Detected - Large Leak (P0093) · Fuel System
- HP Fuel Rail Pressure Low During Power Enrichment (P1093) · Fuel System
- High-Pressure Fuel System Relief Valve Open (P2BAD) · Fuel System
- Injector #6 open circuit (SPN 656 FMI 5) · Fuel System
- Fuel Rail/System Pressure Too Low (P0087) · Fuel System
- Fuel Rail/System Pressure Too High (P0088) · Fuel System
Find a mechanic or related guides
General diagnostic guidance for heavy-duty diesel engines (Cummins, Detroit, PACCAR, Volvo, Mack). Not a substitute for a scan-tool diagnosis on your specific truck.