When troubleshooting a fuel supply problem, which tool should be used to measure fuel pump inlet restriction?

Using a vacuum gauge is an effective way to measure fuel pump inlet restriction. When troubleshooting fuel supply issues, it’s important to determine if there are any restrictions that could be impeding the flow of fuel to the pump. A vacuum gauge can detect the amount of negative pressure in the fuel line, which indicates whether there's suction created by the fuel pump, and can reveal potential blockages or excessive resistance in the lines or filters.

A visual inspection, while useful for spotting obvious issues such as leaks or obvious blockages, does not provide the quantitative data needed to evaluate inlet restriction effectively. A pressure gauge measures the output pressure of the fuel system rather than the inlet condition, and while a fuel flow meter can indicate the amount of fuel being delivered, it does not directly measure the restrictions at the pump inlet. Therefore, the vacuum gauge is specifically designed for this type of troubleshooting, making it the correct choice for measuring fuel pump inlet restriction.