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1987 - 1996 F150 & Larger F-Series Trucks 1987 - 1996 Ford F-150, F-250, F-350 and larger pickups - including the 1997 heavy-duty F250/F350+ trucks

Ignition Coil starting voltage

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Old Aug 15, 2015 | 09:34 AM
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Ignition Coil starting voltage

1991 F-250 5.8 EFI w/TFI-IV ignition system.

Ignition coil is not receiving a full 12V at start-up. Engine started and ran yesterday after boosting the coil with 12V to start. Check Engine light came on within the first minute of idling. Previously we kick started it by crossing the posts on the starter relay.


With a spark plug test light on the ignition coil wire, light only illuminates as the ignition is turned off.
I am guessing a sensor is stealing all available power as the key is turned on.


Next step is to go through each sensor connection.
Any ideas would be appreciated.
 
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