Size of Fuel Pump Fuel pump by itself does not affect spark timing as spark timing is controlled by the engine’s electronic control unit (ECU) based on crank and camshaft position signals from various sensors. But if there were a problem with the fuel pump, it would relate to air-fuel mixing, which will also indirectly affect (the proper) spark timing — in the form of pre-ignition or detonation. If a fuel pump does not provide a reliable, consistent supply of fuel at a set pressure (most are around 40-60 PSI, depending on the vehicle) the end result is a lean fuel charge with insufficient amounts of fuel to match the volume of air present in the combustion chamber. That can lead to a combustion imbalance that creates irregular combustion, i.e., engine knock, which feels much like spark timing problems.
If that lean a/f ratio shows up in spades from an erratic fuel delivery the ECU will have no option but to pull spark and retard advance to stave off detonation at partial throttle and/or higher load, resulting in impaired overall engine dude application. On high MPG or turbo motors that may run at much higher pressures (greater than 100 PSI) when the fuel pressure drops just a little bit, it can result in enough of an imbalance that we lose optimal combustion timing. Research has indicated that lean burning can lose as much as 15% efficiency in an engine since ECU adjustments will further advance the spark timing to maintain knock-free operation.
In the electrical system of the fuel pump, voltage stability can further decrease the flow of the fuel, which indirectly affects the timing adjustment of the ECU. Voltage drops will change the timing of the combustion, as a stable 12v supply to the fuel pump will be critical in fuel delivery. Routine maintenance and inspection of the fuel pump relay and wiring maintain steady voltage and fuel delivery, preventing the potential for timing adjustments that can lower engine output under higher fuel demands.
Though the Fuel Pump does not directly influence spark timing, a properly functioning fuel system helps the engine control unit (ECU) deliver the best combustion timing by maintaining optimal engine efficiency while avoiding drivability concerns related to fuel delivery.