I might be taking the truck to the dealership tomorrow. I was wondering if my injectors are the cause of the knock im hearing. I searched and found some threads but never found anyone who was experiencing the EXACT same symptoms.

Symptoms:
Poor gas mileage
Loud knock when the truck is not warmed up fully
Knock gets a little quieter once its warm but its still there
It can only be heard when your pushing the accelerator
At idle, about every 10 seconds the RPM's jump up about 100rpms like if you just barely tap the accelerator really quick

I tried running a diesel fuel treatment and it seemed to quiet it down a tad but it came back after a while. I can be on 3/4 of a tank and drive maybe 100 miles and its nearly empty and thats with driving around 65mph below 2000rpms. The reason i ask is because if it turns out to not be the injectors, then its going to cost me $150 for the diagnostic and with college coming up (going for pre-law so its pretty expensive) im having to save all the money i can and i dont want it to be something else and i have to fork out the $150. The SES light came on today so im going to get that straightend out when it goes to the dealer. If its the injectors and theyre going to replace them under warranty then i dont see why they wouldnt tell me what the code is that was thrown. Does this sound like an injector problem?

Since you have a 2001, you need to check the date that the truck was put into service. My 01 was put into service 12/00 and thus my warranty has expired.....7 years or 200k I hope for your sake you are still in warranty.

I dont see a date mine was put into service but I had a member on here check my VIN and it said "warranty start date: 07/07/2001. On down the page it said 4/24/2001 was pre-delivery inspection and also the build date is 04/24/2001. I guess this means im BARELY in warranty still. Here is the link to my VIN check incase those dates arent the ones i need. http://www.dieselplace.com/forum/showthread.php?p=2487767#post2487767

Found in upper right hand corner: Warranty Start Date : 07/07/2001

You should (barring any unforseen circumstances) be covered for the injectors (if this is the case)

Thanks. The real question is, are those symptoms of bad injectors? I just want to be atleast 95% sure before i take her in.

my truck is at the dealership now getting injectors done...i had similar symptoms ....loud knock when cold and when hott....fuel milege down 1-2mpgs and small amount of white smoke at start up...good luck with your warranty

Alright thanks. She goes to the stealership tomorrow!

They should cover you, most service managers were getting a spiff for injectors back when my brother's went out.

well thats comforting. They didnt have time to take my truck today so i have to take it to the dealer monday. Hopefully it will be covered. Changing the fuel filter here in a minute to see if it makes a difference.

Changed the fuel filter. It made a HUGE difference. There's hardly any knock anymore. When i dumped the old filter, a good bit of fuel came out and then some brown gunk. It all clumped at the bottom of a bowl i poured it in. I tried to get some on my finger so inspect it closer but it just dispersed and clumped back together. After i cut the filter open and pulled the core out, it was clogged HORRIBLY and that same brown gunk was in the casing of the filter. There were chunks of something that looked like little rust "pebbles". Im not sure what caused that but the truck definately has more get-up-and-go now. It just worries me about the brown stuff. Any ideas on what it could be?

How long since your last filter change, before the one today?

sounds like you got fuel from a mom and pop store, always buy fuel from high volume stations

Not sure when the last fuel filter change was. Im guessing it is the original one. The truck only has 86k miles on it but thats not good on 1 fuel filter. The only gas stations i get my diesel from is cowboys (now kangaroo), texaco, and BP/Shell (shell owns the BP here now). Those are the only gas stations within 20 miles that have diesel.

Fuel filter should be changed every 10k miles.

uh, yeah, brown crap is water and algae fuel gunk. Good thing ya changed it. Did it go to the dealer yet?

better get some biocide in that tank!

No. It should go to the dealer monday. The man i talked to in the service department said their diesel guy was booked today and tomorrow and is off friday so i could take it in monday.