No start: '91 lebaron conv. 3.0l

QuestionEdit

intermittent no start on a 1991 Chrysler Lebanon convertible with a 3.0 v6. seems to be a spark problem. I tried to run some diagnostics using a Haynes Manual (not much info) I used to be a ford mechanic. I accidently discovered when it wont start, if I unplug the power wire to the coil and crank it over, then I reconnect the wires to the coil. the car will then start up. I have used this method more than once and car starts immediately. don't understand what this might be telling me about the cause of the no start. cranking with coil power disconnected seems to be what sets up the car to then start normally.Can hear fuel pump run during no start,also normal crank. only codes 12 21 17 seem unrelated ( used eng. light to get codes). any idea as to the part that would be at fault.

AnswerEdit

Hi Jim, Did the fault codes come out in the order 12-21-17 because if so that suggests that you might want to do it again to see if there might have been a mis-count as they should come out in numerical order. The only thing that ties together the coil and the code 21 is that both the coil and oxygen sensor are powered by the ASD output. Might there be some sort of an intermittent short in the dark green/black wire (and/or the splice it shares with the fuel injectors as well) which you temporarily resolve by handling it when pulling the plug at the coil? I don't have any other reason why the disconnection would encourage a start, so check the voltage on that wire at the coil when it won't start (measure when cranking by use of a pin through the insulation) to see if the coil isn't getting 12V power when it won't start but does when you manipulate the wire. Please 'rate' my answer and consider a nomination of me to be recognized as 'volunteer of the month' as I am in a tight race for that. Thanks. Roland