Testing a fuel pump in cold weather can be tricky; the harsh weather can impact not only the fuel system but also the process of diagnosis. Cold weather, particularly when you’re talking frozen temps, can lead to fuel systems problems — freezing fuel lines, clogged filters, low fuel pump efficiency etc. The lower temperatures reach -20 F (-29 C) – the more your fuel systems can have difficulty, due to their consistency, but mostly due to viscosity, which decreases the speed of fuel flow.
So one of the primary steps to test a fuel pump in cold conditions is to check the fuel pressure using a fuel pressure gauge. Generally speaking, most vehicles should have a fuel pressure of about 35-45 PSI (pounds per square inch). If the reading is lower than anticipated, this can be a sign of an issue with the fuel pump or a clogged fuel filter. Low fuel pressure, for example, often indicates either a failing fuel pump or an obstruction in the fuel line, issues that could be made worse by the cold, according to AutoZone.
Also, an inability for the car to start or maintain idling during cold temperatures may indicate droopy delivery of fuel from the fuel pump. Under these conditions, a fuel pressure gauge can be used to test pump performance. A weak fuel pump may lose the ability to push enough pressure to the fuel injectors when temperatures drop, resulting in rough starts or stalling. Fuel pumps tend to be less efficient in extreme cold, so the pump has to work harder to overcome the increased viscosity of the fuel, added Ford Motor Company.
If you do have an empty tank and want to experiment further, you can measure the resistance of the fuel pump with a multimeter. The current should be suitable so that in winter the working of the pump is not posed to any difficulties. “Voltage drop across the circuit can indicate a failing relay or wiring issue, which could be made worse by cold temperatures. General Motors has also indicated that corrosion or bad connections in the electrical system can have a big impact on the fuel pump in cold weather, causing starting problems.
Alternatively, you could listen to the fuel pump at the initial vehicle ignition. As it primes the system, the pump should make a faint humming sound. A quiet pump or one that makes barely perceptible sounds may be failing, meaning the pump is actually failing to operate, especially in low or cold conditions. There are also evidence of wear and tear on the fuel pump, which is more likely to present itself when the temperatures are low, as indicated by a study by Automotive Repair Solutions.
Lastly, checking the fuel filter is important because cold weather can lead to moister particles that can block the filter and hinder fuel flow. In sub-zero temperatures, condensation in the fuel system can freeze, requiring the fuel pump to work even harder to push fuel through the system. To avoid problems during the cold months, make sure that the fuel filter is clean and replace it if necessary. If so, you might be interested to know that Toyota Motor Corp has long advised to check the fuel filter as part of regular winter maintenance, as a way to prevent fuel delivery issues.
And that involves a combination of checking fuel pressure, inspecting electrical connections, listening for noises and making sure the fuel filter is clear and more in depth depending on the car or van you have and whether you are in cold temps or not. Regular care (like additives created to ward off fuel line freeze-up) can also help prevent problems in the cooler months. You can also visit Fuel Pump for details on how to keep a quality fuel pump.