💉Electronic fuel injection

How it works

Electronic fuel injection has replaced the carburetor on almost all modern motorcycles (widespread from the late 2000s onward, driven in particular by emissions regulations). Instead of drawing fuel in by vacuum, it delivers it under pressure through electronically controlled injectors. A control unit (ECU) continuously receives data from several sensors - crankshaft position and speed, throttle position (TPS), intake air pressure and temperature (MAP/IAT), engine temperature, oxygen/lambda sensor - and calculates the exact amount of fuel to inject and the ignition timing, on every cycle. A pump submerged in the fuel tank maintains fuel pressure, regulated by a pressure regulator. Injection offers much more precise fuel metering than a carburetor, adapts to altitude and temperature, starts without a manual choke, and reduces both consumption and emissions. Failure modes: a sensor feeding the ECU bad data (temperature sensor, MAP, TPS, lambda) and throwing off the mixture, a clogged or leaking injector, a weakening fuel pump, a fouled electronic throttle body or idle control valve, a failing pressure regulator, and, more rarely, an ECU failure. A notable feature: most faults trigger a check-engine light (MIL) and log a fault code readable with a diagnostic tool. Signs: hesitation, rough idle, black smoke (mixture too rich) or flat spots (too lean), hard starting, check-engine light on. Detailed diagnosis and tuning are a job for a professional with the right equipment: they read the codes, test each sensor before replacing anything, and don't touch the fuel map without the skill to do so.

Maintenance tips

• ✓At the first sign of a check-engine light (MIL), have the fault codes read with a diagnostic tool without delay: a skewed sensor can make the engine run too rich and damage it over time.
• ✓Use good-quality fuel and avoid habitually riding down to reserve: the fuel pump is cooled and lubricated by the fuel itself, and a tank that's often nearly empty wears it out faster.
• ✓Have the throttle body and air intake checked and cleaned periodically as recommended: a fouled throttle body degrades idle quality and throttle response.
• ✓Never disconnect the battery or an engine sensor connector while the engine is running: you risk upsetting the ECU or triggering false fault codes.
• ✓Respect the replacement intervals for the fuel filter (often built into the pump module) specified by the manufacturer, to preserve fuel flow and injection pressure.
• ✓Before replacing an expensive sensor, insist that it be tested (measured value compared against spec): on an injected engine, a sensor should be diagnosed, not swapped on a guess.
• ✓Be wary of uncontrolled remapping and add-on tuning boxes: an unsuitable fuel map degrades performance and can damage the engine or catalytic converter.