Starting problems

Car won't start - no fuel pump priming sound

When you turn the key to 'on' you should hear a brief hum from the fuel pump; if you hear nothing, the pump, its fuse, relay, or wiring is likely the problem rather than the engine itself.

Difficulty
Moderate
Time
20–45 minutes
DIY cost
$15–$300
Pro cost
$300–$800

Symptoms

  • No hum from the back of the car when key is turned to 'on'
  • Engine cranks but won't catch
  • May have run out of gas recently or the tank was very low
  • No check engine or fuel light necessarily on

Likely causes

  • CommonBlown fuel pump fuseA simple blown fuse can fully disable the pump.
  • CommonFailed fuel pump relayThe relay switches power to the pump and is a common point of failure.
  • PossibleFailed fuel pump itselfPumps wear out over time, especially if the tank was frequently run very low.
  • PossibleWiring or connector issue at the fuel tankCorrosion or a loose connector near the tank can cut power to the pump.
  • Less commonFuel pump control module fault (on vehicles so equipped)Some vehicles use a separate module to control pump speed and can fail.

What to do

  1. Turn the key to 'on' (not start) and listen carefully near the rear of the car for a 1–3 second hum; try this a couple of times.
  2. Check the fuse box (usually under the hood and/or inside the car) for a fuel pump fuse using the diagram on the cover.
  3. If the fuse is good, locate the fuel pump relay (often near the fuse box) and try swapping it with an identical relay if one exists.
  4. With the key on, listen again after any fuse/relay changes to see if the pump now primes.
  5. If there's still no hum, the pump itself, its wiring, or a control module is the likely cause and needs shop diagnosis.
  6. Avoid running the tank very low in the future, since fuel helps cool and lubricate most in-tank pumps.
  7. Have a mechanic verify fuel pressure directly rather than relying only on the sound test, since some pumps are quiet.
  8. Keep in mind that pump replacement often requires dropping the fuel tank, which affects labor cost.

Tools and parts

  • Fuse puller/tester
  • Flashlight
Electric fuel pump assemblySearch: “fuel pump assembly for [year make model]”
Fuel pump relaySearch: “fuel pump relay for [year make model]”

When to call a pro

If fuses and relays check out with no pump sound, a mechanic can test fuel pressure directly and replace the pump if it's confirmed failed.

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.