# Why does my car crank but not start?

**Verdict:** Drive to a shop this week

- **Most common cause:** No fuel delivery (fuel pump, fuse or relay)
- **Urgency:** This week
- **Typical fix:** $20-$3,000
- **Causes to check:** 6

## Quick answer

When the engine cranks at normal speed but never starts, it is missing fuel, spark, or the sensor signal the computer needs to time them. The most common causes are a fuel delivery problem and a failed crankshaft position sensor. A security or immobilizer fault and, less often, a broken timing belt can also cause it.

## What is happening?

Normal cranking proves the battery, cables and starter are doing their job: the engine is spinning. To fire, it still needs fuel delivered at the right pressure, a spark in each cylinder, compression, and a computer that knows where each piston is so it can time the spark and injectors. The crankshaft and camshaft position sensors provide that timing signal, and the immobilizer decides whether the computer is allowed to run fuel and spark at all.

So a crank-no-start is almost always missing fuel, spark, a timing signal or permission from the security system. Listening for the fuel pump, watching the tachometer while cranking, and checking for a flashing security light narrow it quickly. It matters because cranking for a long time drains the battery, can overheat the starter, and can flood the engine with fuel or push unburned fuel into the catalytic converter. A broken timing belt can also bend valves, so cranking again and again is not a fix.

## What causes it? The 6 most likely reasons

1. **No fuel delivery (fuel pump, fuse or relay)** (most common), $20-$1,300. The fuel pump in the tank must build pressure before the engine can run. A worn pump, a blown fuse, or a failed relay stops fuel completely. Pumps wear faster on cars often driven on a near-empty tank. On many cars you hear a two-second hum at key-on; silence there points strongly to the pump, its fuse or its relay. How to confirm: Turn the key to on (do not start) and listen near the rear seat or tank for a 2-second hum. No hum points to the pump or its fuse and relay. A shop can confirm with a fuel pressure gauge. Fix: Replace fuse or relay, or the fuel pump.
2. **Empty tank or faulty fuel gauge** (common). A stuck fuel gauge or failing sending unit can show fuel when the tank is nearly empty, especially if the car is parked on a slope that moves the remaining fuel away from the pump pickup. It is an easy cause to overlook. Adding a few gallons from a can is the cheapest test before paying for any diagnosis. How to confirm: Add a couple of gallons from a gas can and try again. If it starts, check how the gauge reads against how much you filled. Fix: Add fuel; replace the sending unit if the gauge is wrong.
3. **Failed crankshaft or camshaft position sensor** (common), $150-$400. These sensors tell the computer where the engine is in its rotation. Without the crankshaft signal, most engines get no spark and no injector pulses, so they crank forever without firing. A tachometer that stays at zero while cranking is a strong clue. Failures are often heat-related and may follow earlier stalling when the engine was hot. How to confirm: The tachometer needle stays at zero while cranking on many cars. The car may have stalled while driving before this, and a scan often shows P0335 or P0340. Fix: Replace the sensor.
4. **Immobilizer or key not recognized** (less common). If the anti-theft system does not recognize the key, many cars crank but block fuel or spark. A flashing key or security light on the dash is the giveaway. A dead fob battery, a damaged chip key, or a newly cut key that was never programmed are common reasons. Trying the spare key quickly confirms it. How to confirm: A security light flashes or stays on while cranking. Try the spare key; if it starts, the original key or its chip is the problem. Fix: Use the spare, replace or reprogram the key.
5. **No spark (ignition fault)** (less common), $20-$500. A failed ignition relay, a blown fuse, or a bad ignition module or distributor on older cars can stop all the coils from firing. Single bad coils or plugs cause misfires, not a no-start, unless many fail at once. A shop confirms it with a spark tester, which is safer than pulling plug wires while cranking. How to confirm: Check the ignition and engine fuses in the fuse box. A shop can confirm spark with a simple spark tester in a few minutes. Fix: Replace fuse, relay or ignition module.
6. **Broken timing belt** (rare), $600-$3,000. If the timing belt snaps, the camshaft stops turning while the crankshaft keeps spinning, so valves and pistons fall out of sync and the engine cannot compress air. Cranking often sounds faster and smoother than usual. On interference engines the valves are also damaged. Belts past their replacement interval are the usual cause. How to confirm: Cranking sounds faster and smoother than usual, often after the engine died suddenly while driving. A shop checks by removing the oil cap or timing cover to see if the camshaft turns. Fix: Replace the timing belt (more if valves are bent).

## How to narrow it down at home

1. Check the fuel level and add a couple of gallons if the gauge is anywhere near low.
2. Turn the key to on without starting and listen for the fuel pump hum for about 2 seconds, and watch whether the tachometer moves while cranking.
3. Look for a flashing key or security light, and try the spare key.

## Is it safe to drive?

> **Drive to a shop this week.** This is not a safety problem while the car is parked, but avoid cranking for more than 10 seconds at a time, and stop after a few tries so you do not flood the engine or drain the battery. If it started after a stall in traffic, have it towed rather than driven.

## When does it become urgent?

- You smell strong fuel or see fuel dripping under the car: stop cranking, it is a fire risk.
- The engine cranks unusually fast or sounds different, which can mean a broken timing belt.
- It stalled while driving and now will not restart: have it towed, not jumped and driven.
- Cranking is getting slower each try, which means the battery is draining.

## What will the repair cost?

| Cause | Fix | Typical cost |
| --- | --- | --- |
| No fuel delivery (fuel pump, fuse or relay) | Replace fuse or relay, or the fuel pump | $20-$1,300 |
| Failed crankshaft or camshaft position sensor | Replace the sensor | $150-$400 |
| No spark (ignition fault) | Replace fuse, relay or ignition module | $20-$500 |
| Broken timing belt | Replace the timing belt (more if valves are bent) | $600-$3,000 |

Detailed breakdowns: [timing belt replacement cost](/cost/timing-belt-replacement), [ignition coil replacement cost](/cost/ignition-coil-replacement), [spark plug replacement cost](/cost/spark-plug-replacement).

## What to tell your mechanic

Tell the shop whether you hear the fuel pump hum at key-on, whether the tachometer moves while cranking, whether a security or key light flashes, how much fuel is in the tank, and whether it stalled first or just failed to start. They will read codes, check fuel pressure, test for spark, and look at crank sensor signals on a scan tool.

## How to prevent it

- Replace the timing belt at the interval in your owner's manual, often 60,000 to 100,000 miles.
- Keep at least a quarter tank of fuel so the in-tank pump stays cool and covered.
- Fill up at busy stations and avoid running the tank dry, which can draw debris into the pump.
- Keep the spare key working and replace fob batteries before they die.
- Have a check engine light read promptly, since a weak crank sensor often sets a code first.

## Trouble codes that often go with it

- [P0335](/codes/p0335): Crankshaft Position Sensor "A" Circuit
- [P0340](/codes/p0340): Camshaft Position Sensor "A" Circuit (Bank 1 or Single Sensor)
- [P0230](/codes/p0230): Fuel Pump Primary Circuit
- [P0087](/codes/p0087): Fuel Rail/System Pressure - Too Low
- [P0016](/codes/p0016): Crankshaft Position - Camshaft Position Correlation (Bank 1 Sensor A)

## Frequently asked questions

### What does it mean when a car cranks but won't start?

It means the starter and battery are working but the engine is missing fuel, spark, or the sensor signal it needs to time them. The most common reasons are a fuel pump problem and a failed crankshaft position sensor. Listening for the fuel pump hum at key-on is the best first check.

### Can a bad battery cause a car to crank but not start?

Yes, sometimes. A weak battery can spin the engine slowly enough that the computer, fuel pump or ignition does not get steady voltage. If the cranking sounds slower than normal or the dash flickers, try a jump start first before suspecting more expensive parts like the pump or sensors.

### Can a clogged fuel filter cause a no-start?

Yes, but a fully blocked filter is uncommon. A partly clogged filter usually causes hesitation and stalling under load first, long before a no-start. Many newer cars have the filter built into the pump assembly in the tank, so it is replaced with the pump rather than as a separate part.

### How long should I crank an engine that won't start?

No more than about 10 seconds at a time, with a pause of a minute or so between tries to let the starter cool. After three or four tries, stop and diagnose rather than keep cranking. Long cranking drains the battery and can flood the engine or overheat the starter.

### How much does it cost to fix a car that cranks but won't start?

It can be as little as 20 dollars for a fuse or relay, 150 to 400 dollars for a crankshaft or camshaft sensor, or up to about 1,300 dollars for a fuel pump at an independent shop in 2026. A broken timing belt runs about 600 to 3,000 dollars, more if valves bent.

### How can I tell if my fuel pump is bad?

Turn the key to on without cranking and listen near the fuel tank for a two-second hum; no hum suggests the pump, its fuse or relay. Check the fuse and swap the relay with an identical one if your manual shows how. A shop confirms it with a fuel pressure gauge.

### Can a bad crankshaft sensor stop a car from starting?

Yes. Without the crankshaft position signal, most engines get no spark and no fuel injection, so they crank but never fire. A tachometer that does not move while cranking is a strong hint. The sensor often fails when hot first, causing stalling, before it stops the car from starting at all.

### Can I start a car that cranks but won't start with starter fluid?

Spraying starter fluid into the intake can show whether the engine lacks fuel: if it fires briefly, fuel delivery is likely the problem. It is a test, not a fix, and can damage some engines or cause backfire. Many modern cars and all diesels should not be tested this way.

### Why does my car crank but not start when it is hot?

Hot no-starts often point to a crankshaft position sensor that fails when warm, a weak fuel pump, or fuel vapor in the lines. If the car starts after it cools for 20 to 30 minutes, note that pattern for the shop, since it narrows the diagnosis a lot.

### Is a flooded engine the reason my car won't start?

It can be after many short start attempts, especially in cold weather, and you may smell fuel. Wait 10 to 15 minutes, then try again. Many fuel-injected cars have a clear-flood mode when you hold the gas pedal to the floor while cranking; check your owner's manual first.

## Sources

- [Car Care Council: Car care guide](https://www.carcare.org/car-care-guide/)
- [EPA: On-Board Diagnostics (OBD)](https://www.epa.gov/state-and-local-transportation/vehicle-emissions-board-diagnostics-obd)

## Other car problems

- [Why is blue smoke coming from my exhaust?](https://diagxcar.com/symptoms/blue-smoke-from-exhaust)
- [Why does my car smell like something is burning?](https://diagxcar.com/symptoms/burning-smell-from-car)
- [Why does my car hesitate when I accelerate?](https://diagxcar.com/symptoms/car-hesitates-when-accelerating)
- [Why does my car jerk when I accelerate?](https://diagxcar.com/symptoms/car-jerks-when-accelerating)
- [Why is my car leaking oil?](https://diagxcar.com/symptoms/car-leaking-oil)
- [Why does my car lose power when accelerating?](https://diagxcar.com/symptoms/car-loses-power-when-accelerating)
- [Why does my car shake at idle?](https://diagxcar.com/symptoms/car-shakes-at-idle)
- [Why does my car shake when I accelerate?](https://diagxcar.com/symptoms/car-shakes-when-accelerating)
- [Why is my car heater not working?](https://diagxcar.com/symptoms/car-heater-not-working)
- [Why does my car click but not start?](https://diagxcar.com/symptoms/car-clicks-but-wont-start)

## Repair costs

- [Timing belt replacement cost](https://diagxcar.com/cost/timing-belt-replacement): $500-$1,300
- [Ignition coil replacement cost](https://diagxcar.com/cost/ignition-coil-replacement): $150-$400
- [Spark plug replacement cost](https://diagxcar.com/cost/spark-plug-replacement): $120-$450
- [Camshaft position sensor replacement cost](https://diagxcar.com/cost/camshaft-position-sensor-replacement)
- [Car battery replacement cost](https://diagxcar.com/cost/car-battery-replacement)
- [Crankshaft position sensor replacement cost](https://diagxcar.com/cost/crankshaft-position-sensor-replacement)
- [EVAP purge valve replacement cost](https://diagxcar.com/cost/evap-purge-valve-replacement)
- [Fuel pump replacement cost](https://diagxcar.com/cost/fuel-pump-replacement)
- [Timing chain replacement cost](https://diagxcar.com/cost/timing-chain-replacement)

## How long parts last

- [How long does a timing belt last?](https://diagxcar.com/how-long/timing-belt): 60,000-100,000 miles
- [How long does a fuel pump last?](https://diagxcar.com/how-long/fuel-pump)

## Trouble codes that lead here

- [P0016 Crankshaft Position - Camshaft Position Correlation (Bank 1 Sensor A)](https://diagxcar.com/codes/p0016)
- [P0017 Crankshaft Position - Camshaft Position Correlation (Bank 1 Sensor B)](https://diagxcar.com/codes/p0017)
- [P0018 Crankshaft Position - Camshaft Position Correlation (Bank 2 Sensor A)](https://diagxcar.com/codes/p0018)
- [P0087 Fuel Rail/System Pressure - Too Low](https://diagxcar.com/codes/p0087)
- [P0117 Engine Coolant Temperature Sensor 1 Circuit Low](https://diagxcar.com/codes/p0117)
- [P0191 Fuel Rail Pressure Sensor "A" Circuit Range/Performance](https://diagxcar.com/codes/p0191)
- [P0230 Fuel Pump Primary Circuit](https://diagxcar.com/codes/p0230)
- [P0261 Cylinder 1 Injector "A" Circuit Low](https://diagxcar.com/codes/p0261)
- [P0320 Ignition/Distributor Engine Speed Input Circuit](https://diagxcar.com/codes/p0320)
- [P0335 Crankshaft Position Sensor "A" Circuit](https://diagxcar.com/codes/p0335)
- [P0336 Crankshaft Position Sensor "A" Circuit Range/Performance](https://diagxcar.com/codes/p0336)
- [P0339 Crankshaft Position Sensor "A" Circuit Intermittent](https://diagxcar.com/codes/p0339)

## Terms explained

- [What is Timing belt?](https://diagxcar.com/glossary/timing-belt)

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Source page: https://diagxcar.com/symptoms/car-cranks-but-wont-start
Updated: 2026-11-03
General information, not a substitute for a qualified mechanic.