Complete power loss problem!!!

[SnakePitRacing]

Hoping any of my SVTP Brethren can help me trouble shoot. Last weekend, I was driving my 04 Lightning down the highway at about 67MPH. All of a sudden I had a complete power loss. The truck stayed on for a bit, but I couldn't accelerate at all. I coasted to the shoulder and parked. When I tried to start it back up, it would start immediately, but turn back off when the RPM went down. Like if I turned the key. IE, turn key, RPM goes up, goes all the way on. I sat on the side of the road for a few minutes. After about 10 minutes (while I waited for a tow) I tried it again, same thing. Gave it a few more min, stepped on the accelerator all the way down, and it stayed on. Drove about 10 mi at HWY speed, no problem. Any clues? Here are the particulars...

04 L. 98k mi.
Oil changed about 100 mi ago.
Never had problems before.
Regular oil changes/tune ups performed.
No Check Engine light before or after.

Thanks guys. Really appreciate any input.

 

[Lightning Lad]

Sounds like an electrical issue.

 

[SnakePitRacing]

I went there first. Battery is still good, not Battery light came on, and very other electrical component is on and working. Checked every fuse inside and under hood.

 

[FireGuy]

The gauge sweep with the tachometer you described occurs when the power has been lost or reset. I would start by checking, not just looking but physically checking all the ground connections, especially near the starter, Take each one off clean and reinstall. Be sure the battery is disconnected when doing any electrical work.

Check your charging system and all connections to the alternator. Then check the static and running voltage. Static should be 12.5 or higher and running a minimum 0f 13.8 or higher. Have the battery load tested at a parts store, Auto Zone, O'Reilly's, etc.

My thoughts go towards the alternator or the connections as primary suspects. If the voltage drops enough, it could be closing the fuel relay causing it to die while driving.

There are several people on here and other boards that can add much more insight than me.

Good luck, these Lightnings have a fickle side when it comes to voltage.

 

[SnakePitRacing]

Thank you, Sir. Ill check in tomorrow when Im able to get under it and do so.

 

[SnakePitRacing]

Oh, one more thing. Not a complete Tach sweep. Just the usual 0 RPM, to 3K-ish RPM, back to 0.

 

[RDLightning01]

I had a terminal come loose that caused the same issues.

 

[Darren5.0L]

My thoughts go towards the alternator or the connections as primary suspects. If the voltage drops enough, it could be closing the fuel relay causing it to die while driving.

Good luck, these Lightnings have a fickle side when it comes to voltage.

I chased a problem like this for the better part of a year, threw CPS codes and shut down randomly. Installed a new alternator and have had no issues since, its all in my Ownership report thread located in the section of the forum.

 

[SnakePitRacing]

Thanks guys. Ill finally have tome this weekend to check/clean everything out. Ill check in later.