78 not starting until key is released.
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Junior User
Joined: Sep 2010
Posts: 51
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From: Griffin, Georgia
78 not starting until key is released.
My 78 F150, the brown one won't start. I was driving it daily and parked it for a couple weels. I went drive it one day and it won't start. However when i release the key it fires and cuts off. why am i getting fire only when releasing the key? I changed solenoid, ignition module, and key switch assembly? only other thing i can think of is the distributor, but that doesn't make any sense to me why it would cause that. Any ideas??
Elder User
Joined: Jan 2014
Posts: 898
Likes: 3
From: Chillicothe, IA
First question, had you messed with any wiring prior to it not running proper. It sounds like you are not getting power, or enough power to your magic pixie making circuit. I would defiantly check and clean all grounds, add a few if you haven't already, and replace any factory ones that are missing. The 3 main are from battery to engine, from engine to frame, from engine to cab. Clean the contact area for your duraspark. If that doesn't work, you need to start testing. Putting a meter on the power going to the duraspark and see if you have proper voltage during start.
Tuned
Joined: Sep 2010
Posts: 279
Likes: 8
That sounds like the ignition switch, disable the start circuit (pull the small wire off the starter solenoid) turn the key to the run position and check for voltage at the coil, you should have voltage there, then turn the key to the start position, see if you still have voltage at the coil, if not it's the ignition switch.
Lead Driver
Joined: Oct 2018
Posts: 7,877
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I agree the ignition switch is most likely the problem, or a wire from it. if that's not it the pick up coil can cause this , I had it happen.
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Elder User
Joined: Jan 2014
Posts: 898
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From: Chillicothe, IA
That sounds like the ignition switch, disable the start circuit (pull the small wire off the starter solenoid) turn the key to the run position and check for voltage at the coil, you should have voltage there, then turn the key to the start position, see if you still have voltage at the coil, if not it's the ignition switch.
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From: S/W Missouri, Polk county
Here is some talk about it. But who has an oscilloscope now days? Dura Spark II
Some out of the manual troubleshooting of the DSII scroll down just a bit
https://www.ford-trucks.com/forums/1...l#post17700315
Here is a walk thru and some troubleshooting And an excerpt from it below.
https://www.ford-trucks.com/forums/1...l#post14880906
Note the part about from the above link " Often times, if the pickup fails (which is what you're checking), it will not switch the module while the engine is cranking, but letting off the key collapses the coil, which gives that final spark. If the BLINK test BLINKs, then my test is a moot point."
Some out of the manual troubleshooting of the DSII scroll down just a bit
https://www.ford-trucks.com/forums/1...l#post17700315
Here is a walk thru and some troubleshooting And an excerpt from it below.
https://www.ford-trucks.com/forums/1...l#post14880906
Note the part about from the above link " Often times, if the pickup fails (which is what you're checking), it will not switch the module while the engine is cranking, but letting off the key collapses the coil, which gives that final spark. If the BLINK test BLINKs, then my test is a moot point."
Tuned
Joined: Jun 2018
Posts: 378
Likes: 134
Everytime I've had this happen, it's been the pickup coil. Others mentioned it as well. I have seen it many times. My wood hauling truck just did the same thing this year. The distributor (and therefore pickup) was only a couple months old on that particular truck. They will usually run a while then die. Then wont start, only firing when the key is let go. Then later will start and repeat the process. Sometimes the coils check bad with an ohmmeter. Sometimes not
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