No spark

Tiny
DKELLEY95
  • MEMBER
  • 1995 FORD F-150
  • 4.9L
  • 6 CYL
  • 4WD
  • MANUAL
  • 166,000 MILES
I have a 1995 F-150 with a 4.9 L6 motor. Engine will start sometimes, other times it wont. I pulled a spark plug off and noticed that it has intermittent spark. When it sparks, obviously it will start. Wait a few minutes and it dies. Immediately, I try to start it with a plug wire pulled no spark. As I said, its random/intermittent. I have the 12v I should going to the ignition coil when the key is turned on. I'm thinking something in the distributor. Any ideas?
Wednesday, September 3rd, 2014 AT 3:20 PM

3 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
Have you checked the crank sensor?
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Saturday, January 16th, 2021 AT 12:16 PM
Tiny
DKELLEY95
  • MEMBER
  • 2 POSTS
A crank sensor goes by a different name in this motor. I had hooked up a 12v test light clamp to the positive terminal of the battery and touched it to the negative side of the ignition coil. I then had a friend try to start the truck. I believe the bulb on the test light should blink to represent a switching signal to the coil. However, it did not. This leads me to believe that the pickup coil( aka crank sensor) inside the distributor is bad. The reason I believe it is this rather than the ICM, is because when it does start, it idles and runs fine. The ICM, correct me if I'm wrong, should cause the vehicle to miss if it was bad.
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Saturday, January 16th, 2021 AT 12:16 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
It can still run fine if the ICM is working on and off. However, I feel the same way you do. It does sound like the pick-up coil based on your description.
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Saturday, January 16th, 2021 AT 12:16 PM

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