The Obvious Cause You Might Overlook
It sounds simple, but running out of petrol is one of the more frequent reasons NZ drivers call a breakdown service — especially when the fuel gauge is unreliable or the car has been lent to someone else. If your car cranks strongly but won't start, and you're not sure of your fuel level, this should be one of your first checks.
How to Tell If You're Out of Fuel
- The fuel gauge reads empty or very low
- The car cranks normally and sounds healthy but never fires
- No engine warning lights (if the fuel system had a fault, you'd often see a warning)
- The car ran fine until recently and there's no other obvious cause
Note: some older fuel gauges are notoriously inaccurate, particularly on certain Japanese import models. The gauge can read a quarter-tank while the car is actually near empty.
What to Do If You've Run Out
- Don't keep cranking. You risk running the fuel pump dry, which can shorten its life — fuel lubricates the pump.
- Call a breakdown service or have someone bring you a jerry can of petrol. In New Zealand, AA Roadservice (if you're a member) will deliver enough fuel to get you to a station.
- Add at least 5–10 litres before trying to start — the fuel pump needs to prime the system, which takes a few seconds of cranking.
- With a fresh fuel supply, turn the ignition to the "on" position (not start) for 3–5 seconds to prime the fuel system, then crank. You may need 2–3 attempts.
When the Gauge Is Lying to You
A faulty fuel sender unit (the float inside the tank) is surprisingly common on older vehicles and some NZ-spec Japanese imports. Signs the gauge is unreliable:
- The needle jumps around while driving
- The gauge reads full immediately after filling, then drops to empty surprisingly fast
- The car runs out of fuel with the gauge showing a quarter-tank
A fuel sender unit replacement costs $200–$450 NZD including labour, depending on the vehicle — the tank usually needs to be dropped to access it.
Diesel vs. Petrol: Running Dry Has Different Consequences
On a petrol car, running out of fuel is inconvenient. On a diesel, running dry can introduce air into the fuel system, requiring bleeding (purging air from the lines) before the engine will start. On common-rail diesel engines, this can sometimes happen automatically with repeated cranking, but on older diesels a mechanic may need to bleed the system manually — adding time and cost to a simple fuel top-up situation.
After Running Dry: Check the Fuel Filter
Running a petrol car empty can suck debris from the bottom of the tank through the fuel filter and pump. If you regularly run your car very low, consider replacing the fuel filter as preventative maintenance (typically $80–$180 NZD fitted on most vehicles).