Case 1
Symptoms: The starter and engine both have normal starting speed, but the engine does not ignite; Or sometimes it takes multiple long attempts to start. No fault code.
Fault Analysis and Elimination:
1. Check the fuel line.
When there is no fault code, mechanical faults are usually considered first. For difficult starting, the fuel line is the first thing to think of. If air enters the fuel line, it can cause starting difficulties. In common rail systems, it is relatively difficult to remove air from the fuel line because the hand fuel pump has a very small air removal capacity and requires a long time and effort. Often, the operator may feel that the air has been completely removed, but in fact, it has not been completely removed. According to our actual experience, such cases are not uncommon.
We can try to loosen the return oil bolt of the fuel pump to remove air. If necessary, we can loosen the high-pressure fuel pipe and use the starter to drive the engine to idle to remove air. This will be much faster, but at this time, we need to be careful not to get fuel on the various wire harness plugs. If it is confirmed that there is no air, then we need to consider whether there is a blockage in the fuel line. It is best to check the fuel tank, fuel inlet pipe, oil-water separator, fuel transfer pump, diesel filter, high-pressure fuel pump, high-pressure fuel pipe, injector, and return oil pipe one by one. If there is a blockage, remove it.
Another situation is that if the inner diameter of the fuel inlet hose or return hose is too small or too long, it can cause poor fuel supply and return, which can also make the engine difficult to start or unable to start. In this case, it is necessary to replace the fuel inlet and return hoses that meet the requirements, with an inner diameter of at least 12 millimeters. If it is confirmed that there is no blockage, then check the entire fuel line for leaks.
Fuel line leakage can make it difficult to establish rail pressure, thus preventing the engine from starting. Check for leaks, especially in the injector horizontal cavity, and confirm whether it is caused by installation issues or wear before taking relevant measures. If all the above situations are normal, the fuel line problem can basically be ruled out, unless the fuel quality is too poor.
2. Check the circuit
First, check if the ECU has power. If there is no power, it definitely cannot start. Another important issue is that the fuel pump in the electronic fuel injection system has two PCV valves. If these two valves are plugged in the wrong position, the engine will not start and no fault code will be reported. First, identify the markings on the plug wires. The one with the marking should be close to the flywheel housing. If the marking has fallen off, swap the two plugs and try again. If it starts, it means the PCV valves were plugged in the wrong position.
3. Check the fuel pump installation angle
If the problem still cannot be eliminated, then consider whether the fuel supply timing is correct. Check the fuel pump installation angle or check if the flywheel is the original flywheel.