Gmc

[pmarine]

Hi everyone
I have a 2005 GMC C7500 with a 7.8L duramax. It's loosing power missing and smoking black. I took it to the mechanic and he made me change the fuel filter,fuel rail and it still works bad.Can someone please advise me what to do or check.
Thanks

[RDG]

Since this is a FORD Diesel site, you might want to check out these GM sites:
The Diesel Page - for the 6.2L, 6.5L, and Duramax 6600 (6.6L) GM Chevrolet and GMC diesel engines.

gmc-diesel.com

[Packard8]

Originally Posted by pmarine

Hi everyone
I have a 2005 GMC C7500 with a 7.8L duramax. It's loosing power missing and smoking black. I took it to the mechanic and he made me change the fuel filter,fuel rail and it still works bad.Can someone please advise me what to do or check. Thanks

Hello & welcome. This is the General Diesel area of this forum and there are some very sharp ppl here re MD & HD trucks and non Ford engines. Since your 7.8l is an inline six in a MD truck, I'm not sure you will get much info on the Duramax pickup truck sites mentioned above, but give it a shot. Maybe Birken or Gone Fishin' will chime in. Sounds like a fuel issue to me but I have no experience with that engine....is it throwing any codes?

Good luck!

[Kaliburz]

Hummm.......

07.... I'd hazzard a guess that it's computerized .... so the first thing would be to check the puter and see what it says and go from there.

But if it's "missing" it sounds like it would be the injection timing or possible fuel pressure if it's a common rail I would say..... In the old mechanical IP pumps, if it wasn't timed right.....