1997 f150 4.2L no spark.have power at coil pack also showing rpm. replaced coil pack.

Did you check for B+ volt an ground at ignition module before replacing the coil's ? Videos on youtube showing how to test GM ignition systems

- Won't start
- Check for spark (no spark on any cylinder)
- Check for rpm signal to ECU with scan tool or vag-com (checks good)
- Check for power and ground at coil packs (no power on red/green wire)
- Check fuse 29 (fuse checks good, but is not energized during cranking)
- Check ECM power relay (is getting power and ground to coil side, and power to source pin. It clicks, but no output to load pin)
- Jump relay (vehicle runs)
- Replace relay.

check for spark in cylinders 1 and 4 if none, replace coil pack. If spark is present replace spark plugs in cylinder 1 and 4

a failing coil will show up at the higher end of the rpm range because the faster it has to make spark, the weaker the spark not the other way around
have the fault codes read and save money by not guessing
from your description it could be a fuel pressure / injector ptoblem

Sounds like a bad crank sensor or a bad ignition module. If you have a scanner that can read sensor data, you can crank the engine over and see if there is an "RPM" reading. If there is an RPM reading, then the crank sensor is good...Throw the module away. If there is no RPM, replace the crank sensor.

No spark.This is indication of faulty spark plugs.But spark plugs get power to spark from coil pack. So get the connection between coil pack to spark plugs checked.If it checked out ok then its faulty spark plugs that has to be replaced,but if coil pack has no power then its faulty coil pack that has to be replaced.But if coil pack and spark plugs both checked out ok then this problem is fuel related problem.In this case the fuel pressure needs to be checked.The fuel pressure can be easily checked at any local car garage.If its low then its faulty fuel pump as well as clogged fuel filter,which has to be replaced. The voltage for spark plugs and coil pack in voltmeter will show 12 volts.Its a 12 volt part.If there is no or low volt then there is problem with the part. ------------------ Keep updated with any more queries.Thanks.

Spark plugs get there voltage from the ignition coil packs, more then likely you have a bad coil pack or coil pack boot, pull one coil pack or spark plug wire or boot at a time, if you see a drop in rpm, that one is good, if no drop bad coil pack.

The spark plugs receives power to spark from coil pack.Check the power at the coil pack and also check the voltage at the coil pack with meter.If the coil pack shows proper power as well as voltage then its fault in spark plugs.Otherwise its faulty coil pack.The coil pack receives power from battery.so also check the voltage of the battery it should be exact 12 volt.
If the battery shows low voltage then the battery needs to be re-charged.
Then check out.
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has a coil pack ?
check to make sure you have power coming to the pack and check your ground

change the dist.coil pack and electrnic spark control module autozone 135.99 control module 31.99 for coil pack each