When a generator refuses to start, the cause is nearly always one of nine things, and you can check them in order of likelihood: battery, fuel, fuel tap, choke, air filter, oil level, spark or glow plugs, breaker position, and overload from connected appliances. Here is the checklist our technicians run, in the order they run it.
1. Flat or corroded battery
On electric-start units this is the single most common fault. If you hear clicking or slow cranking, charge or replace the battery and clean the terminals. Prevention is a weekly exercise run, which is the heart of any good maintenance schedule.
2. Stale or contaminated fuel
Petrol degrades in a few months; diesel absorbs water and grows algae. If the machine sat since the last rainy season, drain the old fuel and refill fresh before anything else.
3. Fuel tap closed or tank empty
Obvious, and still a regular find. Confirm the tap is open and fuel actually reaches the carburettor or injection pump.
4. Choke set wrong (petrol units)
A cold engine needs full choke; a warm engine floods with it. If you smell petrol after repeated attempts, open the choke fully, wait a few minutes, and try again.
5. Clogged air filter
Dust is a fact of life on Ugandan sites. An engine that cannot breathe will not fire. Pull the filter; if light does not pass through it, clean or replace it.
6. Low oil shutdown
Most modern units refuse to start, or start and immediately die, when oil is low. Check the dipstick on level ground. This one protects the engine, so thank it and top up.
7. Faulty spark plug or glow plug
A fouled spark plug on petrol, or failed glow plugs on cold-start diesel, gives crank-no-fire. Plugs are cheap; carry a spare.
8. Main breaker or AVR issues
Sometimes the engine runs but no power comes out. Check the output breaker is on. If output is erratic or dead with the breaker on, the AVR may have failed, which is a workshop repair.
9. Overload at start
If the unit starts cleanly but dies the moment load connects, disconnect everything and reconnect one appliance at a time. A machine that cannot hold your load was probably never sized for it; see our sizing guide.
When to stop and call for service
Stop if you find metal particles in the oil, white or blue smoke under load, fuel leaking anywhere, or repeated breaker trips with a modest load. Those are symptoms of faults that get more expensive the longer the machine runs. Our generator maintenance team handles diagnostics, overhauls and genuine parts across greater Kampala.
Frequently asked questions
Why does my generator crank but not start?
Cranking without firing means the engine is turning but not getting fuel, air or compression. Check fuel level and freshness, the fuel tap, filters and the air cleaner first; they cause most crank-no-start faults.
Why does my generator start and then shut down?
The most common cause is the low-oil shutdown doing its job. Check oil level first, then fuel flow and overload. A unit that dies exactly when appliances switch on is overloaded, not faulty.
How do I keep fuel from going stale?
Buy fuel in quantities you will use within a couple of months, keep tanks sealed, and run the generator weekly. For standby diesels, an annual tank drain check removes water and sludge.
