Exhaust, fuel & emissions

Car won't start, no fuel pump sound (no prime)

If you don't hear the fuel pump briefly hum when you turn the key to 'on' before starting, the pump isn't priming the fuel system, which will prevent the engine from starting at all.

Difficulty
Moderate
Time
30–60 minutes to diagnose
DIY cost
$10–$40 for fuse/relay
Pro cost
$300–$900 for pump replacement

Symptoms

  • No brief whirring/humming sound from the rear of the car when the key is turned to on/accessory
  • Engine cranks but doesn't start or even try to catch
  • May have started fine before with no warning
  • Possible other electrical issues if it's a fuse or relay problem

Likely causes

  • CommonFailed fuel pumpElectric fuel pumps can fail suddenly with no warning, especially at higher mileage.
  • CommonBlown fuel pump fuseA blown fuse cuts power to the pump entirely and is an easy first check.
  • CommonFailed fuel pump relayThe relay that switches power to the pump can fail and is often inexpensive to test and replace.
  • PossibleWiring or connector issue at the tankA corroded or damaged connector can cut power to an otherwise good pump.
  • Less commonAnti-theft/immobilizer issue blocking fuel deliverySome security systems can prevent fuel pump activation if they detect an issue.

What to do

  1. Turn the key to 'on' (not start) and listen closely near the rear of the car for a 2–3 second pump hum; have a helper listen if needed.
  2. Check the fuel pump fuse and relay in the fuse box (owner's manual shows locations) and swap the relay with an identical one if unsure.
  3. Check for battery and general electrical issues first, since a very weak battery can sometimes affect this too.
  4. If fuse and relay are good, the pump itself or its wiring is the likely cause.
  5. Have a shop test fuel pump power and ground at the connector to confirm before replacing the pump.
  6. Replace the fuel pump if it's confirmed dead, which usually requires accessing it through the tank.

Tools and parts

  • Fuse puller/tester
  • Multimeter (optional)
Fuel pump relaySearch: “fuel pump relay for [year make model]”
Fuel pump assemblySearch: “fuel pump assembly for [year make model]”

When to call a pro

See a shop for pump testing and replacement if the fuse and relay check out fine, since confirming a dead pump properly needs test equipment.

Safety

Generally low risk

Generally low risk for a careful person. Stop if anything looks different from what this guide describes.

Related guides

Operator provides AI-generated troubleshooting information. It can be wrong. For safety-critical, electrical, gas, structural, medical, automotive safety, or other high-risk problems, consult a qualified professional.