Injecteur de carburant alternatif qui fuit

An injector in a liquefied petroleum gas or compressed natural gas system passing fuel when closed. A gaseous fuel leak behaves very differently from a petrol one and that difference is a safety matter: liquefied petroleum gas is heavier than air and pools in low spaces rather than dispersing, so a leak in a garage or a pit accumulates where people work.

Inside the engine the effect is a rich condition on that cylinder that persists at idle, since a closed injector that passes continues to feed while the engine is barely drawing. A single-cylinder rich fault that is worst at idle and proportionally smaller under load is the pattern, and it will drive the mixture correction to its limit.

These systems hold fuel at pressures far above a petrol system, so depressurise by the correct procedure before opening anything. Leak detection uses a gas detector or an approved solution rather than smell alone — the odourant is added for safety but is not a reliable measure of quantity. Most installations are aftermarket, so trace the actual system rather than a factory diagram, and treat the installer's own documentation as the reference.