Standby generator won’t run - any ideas?

[Headers]

We have a Hyundai generator which has been mothballed for a few years. It has had a general service but it just won’t run.
Oil changed, petrol tank flushed, carburettor cleaned, jets cleared, spark plug checked.
There is an oil sensor but we can’t really check how it works. The oil appears to be at the correct level.

The battery is dud so we a jumping the start off a standby battery.
The machine starts but stops abruptly after a few seconds.
We don’t know what else to do.
Our next step is to take it to our local tractor/ machinery man but we’re not sure they’ll be able to do anything.
If not it’ll be for the scrap heap.

[RobertArthur]

Ignition problem? High voltage leak in the spark plug cable, contact resistance, spark plug cap defective? What type of ignition? Timing issue, capacitor exit?

[Headers]

Ignition problem? High voltage leak in the spark plug cable, contact resistance, spark plug cap defective? What type of ignition? Timing issue, capacitor exit?

OH says it’s magneto. The spark plug is good. The gap is correct. It does fire on a turn of the key but stops very soon afterwards.
Thankyou for your thoughts.

[RobertArthur]

Wiring in a car and in other engines, always the risk of contact resistances with the many spade connectors. Disconnect them, clean them (a spray of MOTIP contact cleaner is also welcome) and reconnect. Also the wiring around the key switch. Don't forget to check the negative battery cable to chassis, where corrosion is not your friend. Old battery removed? In the case of an (almost) dead battery jump starting can help but after removing the cables you're back to square one.

[niemeyjt]

Carbs? Runs when given some extra fuel as choked? Then stalls due to lack of fuel through gunged up jets. A symptom of modern contaminated fuels. Or did you drain tank an run dry before storage?

[rabbit]

I have had a 2 stroke behave like that. I tried cleaning carb jets with carb cleaner but no effect. I bought a replacement carb for about 12€ and it ran fine after that.

[Headers]

Carbs? Runs when given some extra fuel as choked? Then stalls due to lack of fuel through gunged up jets. A symptom of modern contaminated fuels. Or did you drain tank an run dry before storage?

The carb has been cleaned, the fuel tank emptied and partially filled with new fuel. The jets are clean.

[Polarengineer]

If the fuel is gravity fed, there is usually a small filter in the line. If this is partially blocked, it would account for the symptoms of fuel starvation.

[Headers]

If the fuel is gravity fed, there is usually a small filter in the line. If this is partially blocked, it would account for the symptoms of fuel starvation.

we will have a look. Thankyou.

[Spectrum]

Pull the feed hose off at the carb end see if fuel runs out as said it could be the filter or the rubber hoses can collapse on themselves with age, they will allow a trickle of petrol through but not enough to run it.