New injectors and I have a fuel knock

joshd472

joshd472

New member
Oct 10, 2016
254
0
0
I had 3 bad injectors on my passenger bank. I replaced those around Christmas. I held off on the drives bank until a few weeks ago when I got a slight knock and #8 went out of spec so i replaced the drivers side.

Filled up Saturday, drove to work yesterday and on the way home I noticed my fuel knock is back and I got a wiff of raw fuel. Sounds like it's coming from #7 or #8. I didn't get a chance to check the rates yet.

Truck is a LLY has basic upgrades, pcv reroute, intake and exhaust with bully gt that I leave on the tow tune. The injectors came from LDS and I cleaned the high pressure lines with CLR (I was skeptical but they came surprisingly clean). If turn the crappy bully dog down to no power the knock goes away. I'm afraid I got some bad fuel and ruined my brand new injectors. Anyone have any tips on what it might could be? No codes, I've only drove it 15 miles since I noticed the knock so I can't tell if there is fuel in the oil.

This is really sucks because I have been researching and planned on getting EFI and a lift pump this week.
 
Last edited:
stibuilder

stibuilder

New member
Oct 17, 2016
239
0
0
Snoqualmie, WA
I have almost the exact same issue LDS 30% over injectors i have a fuel knock on #8 and its out of spec but i moved #3 to #8 and its still knocking and out of spec on #8
 
joshd472

joshd472

New member
Oct 10, 2016
254
0
0
Yeah that is odd. I don't think my problem has anything to do with LDS, and they have been great, fast shipping, and core returns. The truck ran and sounded great, I was getting 17 mpg hand calculated with 33s with a mix of towing a bay boat and empty. At this point if they are bad, I don't what I'm going to do. I will uninstall the tune and check rates this week sometime.

Does anyone know how I can go about getting the fuel checked?
 
torqued2dmax

torqued2dmax

Member
Mar 26, 2017
646
1
18
Brookville, PA
Remove bed , remove sending unit , look in tank if you have crud on bottom pump most of it out with drum pump put the fuel in small containers for camp fires . Wipe tank clean or remove it to get everything out . Decide if you are going to use sump or draw straw , put on new lift pump with duel filters . Change eng filter to catch what might be in lines . If you think fuel in oil change it and filter . If you still have a problem you can send injectors back to be cleaned . Then get trany built , head gaskets , studs , EFI Good luck!
 
Awenta

Awenta

Active member
Sep 28, 2014
4,090
2
38
CT
You only replaced 3 on the passenger side?

Bad fuel may knock but it won't kill your sticks. Let it run through and keep going.

Could be nothing serious at all. Get the efi. How's the cp3 holding rail?

No real way to get fuel in your oil unless the co3 starts leaking.


Sent from my iPhone using Tapatalk
 
Awenta

Awenta

Active member
Sep 28, 2014
4,090
2
38
CT
Make a log and if there is an issue swap injectors and see if it follows


Sent from my iPhone using Tapatalk
 
stibuilder

stibuilder

New member
Oct 17, 2016
239
0
0
Snoqualmie, WA
I moved #3 and #8 around and still got the issue on #8. I dont think its LDS at all they even overnighted me an injector just in case. Bad tank of fuel wouldn't that make all the holes run funny? I have a FASS with dual filters and it all seems to be something electrical for me i guess. Next im changing cam position sensor.
 
joshd472

joshd472

New member
Oct 10, 2016
254
0
0
Thanks for the advice guys. The truck is a extended cab with 260k miles. If it was in better shape and crew cab I would love to build the tranny and let her eat. But I just can't throw money at this one with a new born. I would love to get a few more years out of it then try to find a nice stock crew cab to upgrade the right way. I don't drive it everyday, it just pulls a boat and skid steer on the weekends.
The tranny was rebuilt right before i bought it the guy had to the paper to prove it but the paper work said it was "built" but I had tear into bc they didn't replace the C2 piston and it has what appears to be the stock torque converter in. Shifts great, temp is great and I've put 10k miles on it with almost always dragging a boat or skid steer and the fluid looks great. Clutches looked brand new also. I just don't think it's "built" so if I got EFI it would be transsafe tuning.

Awenta I don't know what my rail pressure is the bully dog has a fuel pressure reading but I can't find out what that reading actually is. It will build and hold 21k but I don't know if that it accurate bc at idle it says 3.7 and my dash commander app say 4.3 on rail. I haven't fooled with checking because when I bought the truck I had a return test done on it and the tech told me the 3 were bad but the truck held ~26k rail when he commanded it. I don't suspect the CP3 is bad bc I can gap my father in laws stock LB7 pretty easy on my stock tune but I will definitely find out.

I replaced all 4 injectors on the passenger bank then all 4 on the drivers bank a few months later along with a new filter both times. The truck ran great for about 3 weeks until I filled up again.

The new born and work has kept me super busy. I think at this point I will pull rates tomorrow and as long as none of them are crazy I will see how much rail I'm holding at WOT with DC app, change the oil and filter, uninstall the tune, and run this tank through and see how it does. Then If that doesnt help. I will do the tank cleaning as mentioned above and send the sticks back to LDS to get cleaned and get a lift pump Any one know the price they charge to clean them?

Again guys thanks for the advice. I've learned a lot from this place and try to contribute when I can. I've got to do more research on EFI to see if I really want to drop the coin on it but that's another topic on its own.
 
joshd472

joshd472

New member
Oct 10, 2016
254
0
0
Another important thing I forgot to mention is no smoke except for a tiny black puff at WOT.
 
Last edited:
joshd472

joshd472

New member
Oct 10, 2016
254
0
0
Took longer than expected but I finally got a chance to check out the truck yesterday. All balance rates are perfect. I built 24k rail at WOT and I'm getting 18 mpg hand calculated with mixed driving. Uninstalled the bully dog and it runs a lot quieter now.

Think it was all just bad tuning on the bully dog. I took it off, lift pump, is on the way and I'm looking into EFI soon :woott:
 
joshd472

joshd472

New member
Oct 10, 2016
254
0
0
Kory is who I was planning on using unless someone knows of anyone better for my needs. I don't want anything crazy, stock, tow, economy, and mild (60-80 hp) Mainly wanting a little more throttle response and a good clean mid pull.

Main thing i don't like with with the stock tuning is the delayed throttle response and week mid. Seems like it falls flat in the mid range and kicks back up on top.
 
You must log in or register to reply here.
Top Bottom