What does it mean?
Some diesel engines use a distributor injection mechanical fuel pump to generate the high pressures required to inject fuel directly into the cylinder under compression and are usually driven directly by the timing chain. Each pulse of the fuel pump is timed to coincide with an injection pulse, and can provide as much as 300 MPa (3,000 bar or 44,000 psi) to the fuel injectors. This type of fuel pump is very compact, including both low- and high-pressure pumps and fuel pressure regulating device.
Bosch VP30 Distributor Injection Pump Injection pump timing and pressure is directly related to engine speed because it is driven by the timing chain, so there must be a way to advance injection timing. This is accomplished by the fuel timing device, which changes the rotation of the pump outlets in relation to the input drive.
In most modern vehicles, injector advance, that is, fuel timing, is controlled by the fuel timing solenoid valve, which is controlled by the ECM (engine control module), based on engine speed and load. Fuel timing can be advanced by as much as 25° BTDC (before top dead center), when measured from the crankshaft. Fuel Timing Solenoid Action The ECM uses fuel pressure readings to modulate fuel pressure, via the fuel pressure regulator, as well as to monitor the function of the fuel pump itself.
If the ECM detects a problem in the timing of the pulses, it interprets this as a fault, setting a DTC (diagnostic trouble code). DTC P0149 is defined as “Fuel Timing Error.”