Hi, 2003 4.2 F150 6cyl 159,000 miles. New alternator and battery and starter and starter relay. Turns over but won't start. I was thinking coil pack when neighbor said pull wire off spark plug wir and put screwdriver inside wire. Bring close to metal and turn ignition key. If it arcs to screwdriver coil pack is ok. It arced. is this an accurate test for coil pack??
Check your fuses and relays for fuel injection and fuel pump. Theres a scrader valve on your fuel rail I believe. Turn the key on to ignition but don’t start it. Wait 4-5 seconds and turn it back off. Repeat this process 3-4 times. Hit the release on that valve and see if fuel sprays out under pressure. If none or a trickle then you have a fuel pump/filter issue. On older vehicles if you hold your ear to the filler nozzle sometimes you can hear a fuel pump kick in for 3 seconds when someone turns the key to ignition. If you hear it then chances are its ok.
Do you think the spark check is a good sign that the coil pack is ok?
Yes, it’s not the preferred method with newer ignition systems but it does mean your getting spark.