A friend left work today and made it about 3 miles before his 6.2 slowed to 200 rpm. We tried to limp it onto a trailer but ended up winching. When we got to his house, about 30 minutes, it fired right up. Good to go, right?, nah, as soon as we got it unload under it's own power, it dropped back to 200. It was maintaining 200 rpm and I was looking in from the passenger side touching wires, grounds, vacuum lines ect. when we heard a tick/snap noise. As we continued to look, listen and feel, I saw a small spark toward the front of the alternator. About 30 seconds later I saw another tiny spark toward the alternator, I say toward because I wasn't looking directly at it when it happened. He had the alternator tested 8 times and every time it diagnosed good. No codes showed on the scan tool. Anyone have a clue or suggestion?

 

Sounds like a bad ground, I looked at mine and I can't tell where the negative cable is tied to the motor but that's where I would start looking. Mines a 2wd so I can't get under it. It can also be a bad ground connection inside the alternator, you will have to take it apart to see it.

Denny

 

So, it ran good for bout 45 min. Then I received this text:

"So....trucks still not running good after cleaning of connections, MAF, TPS, O2 Sensors, Crank sensor, fuses, relays, ECM, and associated wiring all checked good. All that's left is fuel pump wiring from the relay to the pump or the pump itself. Gonna drop the tank and check wiring then pump.

And, some f***-face engineer that decided "we don't need a Schrader valve on the fuel rails to check fuel pressure"

 

Figured I would give the update and solution. Fuel pump was replaced and still ran bad. He took the MAF sensor out and found a bug in it.

 

Thanks for the update.

 

Very good to know, but all that work!

 

He called it his $350 bug. Ha

 

The real mystery is, how the H3LL did that bug get past the air filter? Stock filter box? Aftermarket hot air intake?

 

All stock, he has only owned it about 2 months and has not messed with the filter. It was all sealed good when he changed it after this ordeal.