A couple weeks ago, went out in the morning and the truck wouldn't start. First time since I've owed it that this has happened.

It sounded like it wanted to start. Nice and strong starter. So at first I thought it could be fuel. Pulled the fuel line and it was definitely getting fuel.

Took out the multimeter, almost 12.8 v at battery. Pulled the fuse, it was good. Checked the live side of the fuse and got 12.6v there. Then I checked the always live wire at the coil. 12.6v there. Then I pulled a plug wire to see if I could get any aching from the coil to the wire. Nothing. So I checked the trigger wires coming into the coil. All seemed to be working...

I decided to get a new coil pack and replace it. Plugged everything in and it still didn't work. I picked up the old coil pack and noticed some rust along the matting surface. Not sure if this was a heat sink or a ground. But I took the new one off to look for rust on the opposite matting surface. Most of that surface is a compound resin material. Except in the top right corner, closest to the driver. There is a metal area and it was rusty and dirty. I cleaned up this area and reinstalled the coil. And it fired right up. I've driven it every day for the last two weeks.

Woke up this morning and it wouldn't start. Checked all connections... Everything is the same. Pulled the coil, there wasn't anything to clean under it. I added a little dialectic grease to that corner, screwed it all down and it still won't start...

Do you guys think I'm blowing coils? Or do you guys think I have a bad connection or ground somewhere?

 

I pulled the new coil pack and ohm tested it. 1.5 on first prong, 1.5 on second prong, 0.8 on third prong.

Replaced the new coil with a new new coil... Still won't fire up.

Can anyone confirm what color the "always live" wire going into the coil will be?

The colors of the wires going into the coil are, from the fire wall to the front. Red/green; Orange/ thin Red: Orange/thin green: Orange/thin white....

I think it's strange that it's not all orange wires are signal wires and the red wire wouldn't be the live wire. But all the things I can find say that the live wire will be the first wire towards the front of the truck.

Anyway, I just went out and tested the front wire (orange/thin white) and the rear wire (red/green) and both were a steady and consistent 12v .

So now I'm thinking it's the crank position sensor or the relay...

Could use a second opinion on this.

 

Good trouble shooting with the volt meter.
Seeing as how you seem to like trouble shooting & turning your own wrenches, borrow, or come by the inexpensive but powerful ELM scan tool & running FORScan diagnostic software on the viewing device of your choice, as discussed here https://www.ford-trucks.com/forums/1...-scantool.html, have it scan all of the vehicle computer/controllers for trouble code clues & post All code Numbers, as they can help focus your trouble shoot.
Don't toss any more parts at this problem on a hunch.

 

Ok. Ordered the ELM tool... Should be here tomorrow. I'll probably still buy the CPS because it's cheap and it's quick to change. I don't mind spending $12 on a hunch. I tried switching relay with a different (but same style) relay and it didn't help. So I'll spend the $12. While I wait for the ELM to show up.

 

IIRC, the wire closest to the firewall should be constantly hot. A quick and easy way to test the crank sensor is to see if the check engine light turns off while the engine is cranking. It's supposed to turn off. If it stays on while the engine is cranking, the ECM is not getting a signal from it. You can also plug in a scanner and view live data and see if you're getting an RPM signal while cranking. If the RPM stays at "0" while cranking, the ECM is not getting a signal from the crank sensor.

 

Hmmmm, the Check Engine Light kinda flash's on and off, intermittently. No consistency to how it flashes.

I think my wife is going to change the sensor while I'm at work.

 

Changed the Crank Position Sensor and it fired right up.

 

Thanks for the update.
What brand did you use?

 

I got it from the local AutoZone so I'm guessing it was an ACDelco but I'm not near the box right now.

 

OK, good feedback on replacing the crank sensor & to hear all now seems well.
Did you get the ELM, hook it up & perform a scan, before replacing the sensor?

 

The ELM just got delivered by Amazon about 15 minutes ago. I haven't had a chance to use it yet but I plan on playing with it this week.

 

Have you had time to get acquainted with the new ELM scan tool addition to your electronic tool box?