no spark on a 98 4.2L

garmar60 · #1 (**permalink**) 10-30-2005, 10:42 PM

I have a 98 F150 with a 4.2L. some times it will start most times not. when it wont start it has no spark (tested with a inline spark tester on a plug). i have replaced the crank position sensor. i have 12V to the + side of the coil. i do not have voltage to the three - side coil wires (best i can tell). I also do not know if i checked the power to the crank sensor correctly but i did not have any voltage between the 2 wires or either wire to ground. is the pcm bad? is there anything else in the spark circuit i should check? Were do i go from here?
Thanks in advance for the help.

Gary

bbossow · #2 (**permalink**) 11-10-2005, 12:01 PM

I have a 1997 f150 with the exact same problem. Everything has been checked. I to am wondering if it the PCM.. have you made any progress on yours? Bruce

BrianA · #3 (**permalink**) 11-10-2005, 07:35 PM

I'm confused.

The 4.2 doesn't have a coil. It has HEI - a coil pack that sends spark to each plug.
So I'm not sure what coil you are talking about.
Anyways, I know some guys have had the coil pack go bad. You might want to look deeper into the possibility of that being the problem.
Let us know if/when you get it fixed.
Thanks!

bbossow · #4 (**permalink**) 11-11-2005, 03:35 PM

hello, it actually was the crank shaft sensor. I tested it and it was bad and replaced it and now the truck runs great..

garmar60 · #5 (**permalink**) 11-11-2005, 10:17 PM

I replaced the pcm and it runs great. I had replaced the crank sensor after testing and determining that the coil pack was good. i also tested the wires from the pcm to the crank sensor to ensure that there were no shorts in them. it seams that if you dont have voltage from the pcm to the sensor then the pcm is bad. i got my replacment from advanced auto for 150.00. thanks for the help

gary

BrianA · #6 (**permalink**) 11-12-2005, 01:08 AM

Great news.
Thanks for the report of the fix.
Happy driving!