I have a 2003 Ford F150 5.4 liter engine v8, was driving and it just died on me and wont fire, I have checked the spark plugs and know they need to be replaced, if replaced and still wont fire what else could be wrong?
Check fuel pressure
Bad plugs will not shut the engine down. All eight of them are not going to stop firing at the same time. Try some starting fluid to see if you need ignition or fuel.
GOD NO! DON'T USE STARTING FLUID! Don't use anything Ether based at least! Dangerous stuff. Remember the fire triangle: Fuel, air, heat. Without one of these, the engine won't run. Carburetor sprays will generally start and run an engine for a moment indicating a lack of fuel. Just unplug a vacuum line at the intake manifold, using the straw, spray into the port for about 2 seconds, replace the vacuum line and attempt to start. If it tries to run, you have a fuel delivery concern. Your Ford is equipped with a fuel shut-off (Impact) switch. Check that switch first if you're not getting any fuel. There are also relays and fuses involved. Your spark plugs are fired by individual coils that are directly controlled by the PCM. Even completely worn plugs will fire.
Spark plugs will not go out all at once, so your problem is not there. Your problem is either with fuel delivery or spark getting to the plug. Even a gummed up air filter will not cause the engine to die. Lacking the proper equipment to test if spark it getting to the plug is possible. It involved a 3 penny nail and the exhaust manifold. If you don't know how to accomplish it, I will not add any further suggestions. But your problems does seem to be electrical/electronic.
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