Instead of looking for a single pressure number, focus on these key points:
* Consult your repair manual: This is the best source for the proper fuel pressure specifications for your truck. It will likely give pressure ranges at idle and potentially at higher RPMs.
* Use a fuel pressure gauge: You need a gauge designed for fuel system pressure testing. It needs to be capable of measuring the appropriate range (likely in the 30-60 PSI range for a 5.4L, but this is not definitive). Incorrectly connecting a gauge can be dangerous.
* Testing procedure: The manual will describe the proper procedure for testing fuel pressure. This often involves connecting the gauge, turning the key to the "on" position (engine off), and observing the pressure. There might be additional steps, such as testing at various engine speeds.
Simply finding a number online without knowing the exact testing conditions won't be helpful and could lead to misdiagnosis. Safety is paramount when working with fuel systems. If you are not comfortable performing this test, take your truck to a qualified mechanic.
