To check for a clogged fuel pump line, the first step is to observe the fuel pressure at the fuel rail. For most vehicles, the ideal pressure ranges between 30 to 50 psi, depending on the model. If the fuel pressure is below the specified range, it would mean that the Fuel Pump line is partially or fully clogged. For instance, a blockage in the fuel line was indicated in a Chevrolet Silverado when the fuel pressure dropped from 45 psi to 20 psi.
You can then check the flow rate of the fuel pump. A line that is restricted creates low fuel flow, where not much fuel is being passed to the engine. Whenever your car is experiencing poor acceleration or rough idling, the primary cause is normally due to fuel starvation brought by a clogged line. In fact, BMW reported how fuel flow problems are seen in those vehicles whose fuel lines are either blocked or had a high level of contaminants.
Another helpful diagnostic approach is the fuel line inspection itself. You visually examine the fuel lines to determine if any damage, cracks, or debris blockage can be seen. The line could be blocked by dirt, rust, and even water. It was true in Toyota Corolla 2005-2009, whose fuel lines get clogged with rust in states with a lot of humidity; this eventually results in problems in fuel delivery. If the fuel line looks dirty, then replacing or cleaning it might be required.
Another critical diagnostic tool is the use of a fuel pressure gauge. To conduct the test, attach the gauge to the fuel rail and then turn the key to the “on” position without firing the engine. If the gauge shows no pressure or fluctuating pressure, the line might be clogged. This diagnostic method is used by Ford Motor Company in their service manuals to confirm fuel system faults.
If you notice low fuel pressure, or poor fuel delivery it is also necessary to check on the Fuel Pump. A major contributor to these problems that affects fuel flow is that the fuel pump filter may block. For example, a fuel filter blockage in Honda Civics caused fuel delivery to fail, which affected the efficiency of the Fuel Pump, leading to engine misfire.
Lastly, check the fuel injectors if there is no problem with the pressure gauge and filter. Clogged fuel injectors, due to junk inside the fuel line, would give similar symptoms to that of a blocked fuel line. In 2018, Audi had a service recall after customers complained about lousy performance by their car engines, which was attributed to clogged injectors resulting from contaminants in the fuel lines.
In the end, when faced with a potentially clogged fuel pump line, the three most important things are fuel pressure checks, visible inspection of the fuel lines for blockages, and fuel flow testing. If these tests prove low fuel delivery, it may be time to clean or replace the Fuel Pump and fuel lines. For high-quality Fuel Pump replacements, visit Fuel Pump.