"pulsing" when driving 35-40 & 55-60

[kboreen]

I have a 2004 GMC with the old LB7 Duramax. It has 39k miles...recently I have started to notice it "pulses" when driving 35-40 & 55-60. Not big jerks...but just enough to sense something isn't right.

I talked to the service department at the dealer...when I started to explain the problem he said "it pulses right?". He said he had two other trucks acting the same way. He said "GM is working on it" "they think it has something to do with the EFI".

Anyone else have any experience with this?

[More Power]

Sounds like your dealer is blowing smoke....

With stock power, my LB7 doesn't "pulse" at any speed. However, with added power it'll hunt at times for the correct speed while on cruise, due to overshoot/undershoot.

I'd change the fuel filter as a first step in troubleshooting.

Jim

[kboreen]

Thanks for the reply Jim...that will be my first step...my current filter is a Hastings (FF1220) and has 10k on it...any recommendations on a new filter?

[More Power]

Ask for the new "dual media" type filters when ordering replacements.

The following vendors all carry the new dual media filters.

http://www.kennedydiesel.com
http://www.usdieselparts.com
http://www.lubespecialist.com
http://www.oilguard.com

In addition, be sure to check the Vendors Area (http://www.thedieselpage.com/vendors/main.htm) for any I may have missed.

Good luck,

Jim