Shutdown faults
Generator Starts Then Stops
If your generator fires and then shuts down, a protection, the fuel supply or a sensor is usually behind it. Something let the engine run, then stopped it, so this is neither a no-start nor an engine that cranks without firing. We read the shutdown alarm first, then check oil pressure, temperature, fuel delivery, engine speed, charging and the load.
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- We read the shutdown alarm first
- Fuel faults told apart from protections
- Written quote before any work
- Onsite across Gauteng
After it fires
Generator starts and stops after a few seconds
Timing is the first clue. A shutdown a few seconds after start often comes from oil-pressure detection, a fuel solenoid that drops out, or a controller that does not see the signals it expects once the engine turns. A shutdown after a longer run more often points to the fuel supply, the temperature or a load the set cannot hold.
Keep the controller message. If you clear it without noting it, you lose the reason the set stopped. A sensor can be wrong, and it can also be right, so we test both possibilities.
For stops that come and go, tell us the conditions: off load, on load, after a set number of minutes, or only when one particular machine starts. That pattern tells us which test to run first.
Fault guide
Generator starts then stops: what it can mean and what to do
When the engine runs for seconds or minutes and then shuts down, a protection, a fuel supply that cannot keep up or a faulty sensor is usually behind it. We read the alarm that stopped it before we change anything. This guide separates what you can safely notice from what a qualified technician tests. One symptom never proves that a particular part has failed.
Symptom, likely cause and repair
Find the line closest to what you see. The cause is the most likely one, not a diagnosis: testing confirms it before any part is replaced.
| What you see | Likely cause | Usual repair |
|---|---|---|
| Stops within seconds, with an oil pressure alarm | Oil pressure not proven in time: a real low level, or a faulty sender or switch | Low oil pressure diagnosis |
| Runs for a few minutes, then dies | Fuel starvation from a blocked filter, an air leak or a failing lift pump | Fuel system repairs |
| Stops as soon as the start button is released | The fuel solenoid hold circuit is not keeping fuel on | Fuel solenoid repairs |
| Stops once the engine warms up, with a temperature alarm | An overheating shutdown from the cooling system | Cooling system repairs |
| Stops with an overspeed or underspeed alarm | Speed sensing, governor settings or the controller | Controller repairs |
01
What you may notice
- The engine starts, runs briefly and shuts down
- It stops after a set time with an alarm on the controller
- It runs off load but stops when the building connects
- It stops at random, sometimes after a long run
02
Possible causes
Any of these can produce the same symptom. Testing decides which one applies.
- A genuine low oil pressure or high temperature shutdown
- A faulty sensor or sensor wiring giving a false shutdown
- Fuel starvation: blocked filters, a failing lift pump, air leaks or a low tank
- Over-speed or under-speed protection from a governor fault
- A load the set cannot carry, tripping the protection
- Charge-alternator or controller configuration faults
03
What you can safely check
Look and note only, from outside the canopy. Do not open panels, covers, fuel lines or the cooling system.
- How long does it run before stopping, and is it always the same time?
- Which alarm or warning light shows after it stops? Photograph it.
- Does it stop with nothing connected, or only when load is applied?
- Has anyone topped up the oil or coolant recently?
04
Stop using the generator and call if you notice
- A low oil pressure or high coolant temperature alarm
- Knocking, grinding or a sudden change in engine sound
- Steam, coolant or oil leaking from the set
- Repeated restarts by the controller after an alarm
If it is safe to reach, stop the generator with its normal stop control or emergency stop, keep people away, and call a technician.
05
What a qualified technician typically tests
These are technician checks, not steps to try yourself. Several involve live electrical measurement, fuel or pressurised systems.
- Logged alarms and the shutdown that actually stopped the engine
- Real oil pressure and coolant temperature against the sensor readings
- Fuel delivery under running conditions, filters and lift pump
- Engine speed and governor behaviour
- Load test, where safe, to see whether the stop follows load
06
Common repair categories
The repair follows the test result. These are the services this symptom most often leads to.
07
What to send when you book
- Your suburb and how we reach the generator
- Make, model and kVA from the data plate (a photo is ideal)
- Fuel type: diesel, petrol or gas
- How long it runs before it stops
- A photo of the alarm shown after the stop
08
Related faults and services
Not sure which symptom fits? Try the generator symptom finder.
Safety before you check anything
- Exhaust contains carbon monoxide, which you cannot see or smell. Run a portable generator outdoors only, away from doors, windows and vents, and never run any generator in a house, garage or other enclosed space.
- A standby generator set to automatic can start at any moment, when the mains fails or on its exercise timer. Keep the canopy closed and stay clear of fans, belts and the exhaust.
- Generator output, the changeover and the control panel can be live, and some parts hold stored electrical energy after shutdown. Leave panels, covers and wiring closed for us to open.
- The engine, exhaust and coolant stay hot after running. Never open a radiator or coolant cap on a hot engine.
- Do not refuel a running or hot generator. If you smell gas at a gas-fuelled set, do not operate switches; leave the area and contact your gas supplier.
Carbon monoxide guidance: US Consumer Product Safety Commission: Generators and engine-driven tools (carbon monoxide).
Send the details on WhatsApp
This opens WhatsApp with a short message already typed: brand, model, capacity, symptoms and suburb. Fill in what you know and send it. Blank lines are fine.
- The data-plate photo is added inside WhatsApp after the chat opens: tap the attachment or camera icon and choose the photo. A link cannot attach the photo for you.
- Take the photo only when the generator is switched off and has cooled down. Do not reach over or into a running or hot generator, and keep away from the exhaust.
- A standby generator set to automatic can start by itself when the mains supply fails. If you are not sure how it is set, photograph the plate from a distance or send a photo of the whole set instead.
Typical repair costs for this fault
Published ranges, last reviewed October 2026. The callout is R400 – R700 in business hours and R700 – R1,400 after hours, and it is waived if you accept the quote. Your written quote after diagnosis is the price that applies.
- Fuel filter replacement
- R300 – R800
- Fuel system cleaning and polishing
- R1,500 – R3,500
- Control panel repair or reprogramming
- R3,500 – R14,000
Step 9: book a diagnosis visit.
Related Pages
Fuel, heat, speed and the controller
- Fuel Solenoid Repairs Hold coil or shutoff that drops out
- Low Oil Pressure Alarm that stops the engine
- Fuel System Repairs Filters, air and delivery
- Generator Overheating Temperature shutdowns
- Low Frequency Speed falls and the set will not hold
- Knocking Noise A new sound before it stops
- Controller Repairs The alarm and the module
- Generator Fault Finding How we separate the symptoms
Common Questions
Questions about a generator that starts and then stops
Why does my generator start and then stop?
Because a protection shut it down, the fuel supply fell away, or it met a load it could not hold. We test to find which one, rather than guess.
It only runs for a few seconds. What does that suggest?
Usually oil-pressure detection, a fuel solenoid that drops out, or a controller input that is not satisfied after cranking.
It runs for a while and then dies. Is that the same fault?
Not always. A later stop more often comes from the fuel supply, the temperature or the load than from a start interlock.
There is an alarm on the screen. Should I reset it and try again?
Photograph the alarm first. Resetting it without a record slows the diagnosis, and restarting into a real low-oil or high-temperature fault can damage the engine.
Can dirty fuel make it start and then stop?
Yes. A partly blocked filter can let the engine fire and then starve it. We check the filters and look for air leaks before we replace any pump.
Can I bypass the oil-pressure switch to keep it running?
No. That protection stops the engine before it damages itself. We test the real pressure and the sender instead.
It only stops when I switch the building on. Where do I look?
That is a load-related stop. We check the frequency, the voltage, fuel delivery under load and the breaker, and our trips-under-load guide explains the pattern.
Still unsure what the fault is? Call or WhatsApp 082 057 4605 for onsite diagnosis.
Service Areas
Onsite visits across Gauteng
We come to your generator anywhere in Gauteng, 24/7. Choose your region for local suburbs, call-out details and the faults we see most there.
What to send before we attend
These details help us plan the visit and bring the right parts. Send what you can on WhatsApp; if you can’t find the model number, we still book the visit.
- Location
- The suburb or site, so the visit can be booked in the right area.
- Make and model
- The generator brand and model, if they are known.
- kVA
- The size printed on the data plate.
- Fuel type
- Diesel, petrol, LPG, natural gas, or dual-fuel.
- Controller model
- The module name on the panel, when it is visible.
- Fault or alarm
- What the set does, and any text on the screen.
- Photos
- The generator, the data plate, and the controller or alarm. Send these on WhatsApp.
Book a Visit
Tell us how long it runs
A few seconds, several minutes, or only once the load connects: each points to a different first test. Include any alarm text.
- Call
- 082 057 4605
- Message us on WhatsApp
What happens next
- We reply with questions about the generator, or to book a visit.
- A technician comes to you. For a breakdown we arrive within 1 hour.
- The fault is diagnosed on site and you get a written quote. No work starts until you accept it.
Charlie, lead technician: Degree in Mechanical Engineering, Degree in Electrical Engineering, Diesel Plant Fitter. Generator specialists since 2000.