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09-04-2010, 10:22 PM #1
2003 LB7 DuraMax having trouble shifting up at 3000RPM
I'm new to Diesels. I have a 2003 Silverado 2500HD DuraMax. Everything in it is stock. It has 153K miles. I recently had 4 of the fuel injectors replaced. The others tested out good. The air filter is almost new (about 3K miles - Fram ToughGuard).
Earlier today I was parked up a steep hill and had less than 1/4 tank of gas. To make a long story short, the truck died on my right after cranking and it took some work to get it started, but after adding fuel it finally cranked.
My question is this: After getting it started back up I drove the truck around and decided to test the acceleration. I noticed that when I'd floor it (at about 20mph) the truck would accelerate until it got to about 2900-3000 RPM and then act like it was choking out: It would sit at that RPM range and start loosing power. As soon as I let off the gas slightly and the RPMs dropped to about 2500 it shifted up and the turbo kicked in. This is the first time I have noticed it do this. I normally don't floor it (gradually accelerate and let teh turbo kick in), but this time I wanted to push it a little more and see what it had. My thinking is that it should have shifted up regardless of the RPMs. I had about 1/2 a tank of fuel when I was testing the acceleration.
Any comments / suggestions would be much appreciated.
2003 Chevy Silverado 2500HD LT 4x4, Crew Cab
6.6L Duramax Diesel (LB7) with an automatic Allison 1000 5 speed.
Spray-in bed liner, S&B Air Filter, Homemade CAI ram scoop, ball hitch for Gooseneck
Black toolbox, metallic-black bowtie, 5.5" NV-200C Bumper Off-Road lights behind a blacked-out grille
285/75R16E BFG A/Ts
Future Upgrades: Exhaust, CAI, programmer, intercooler, torque converter
09-07-2010, 01:56 PM #2
Just an update
Just wanted to post an update.
I ended up replacing the fuel filter (per a recommendation from another site) and there was a lot of debris that came out from the old filter. Unfortunately, the problem got worse with the new filter.
After installing and priming the new filter the turck started immediately, but died after less than a minute of idling. We had a lot of trouble starting it back up (even with re-priming). I ended up having to get 2 new batteries. The truck finally fired back up after re-priming and installing the new batteries. I pressed on the gas gradually to see how it would do at the different RPMs (Vehicle was on level ground, in Park. RPM Ranges went from idle - 3000 RPM). Everything sounded good and there didn't seem to be any hesitations. I decided to drive it around to make sure everything was in good order. The truck died on me after going about 400yds. After priming and restarting it I got another 1/4 mile and it did the same thing. I noticed that it would die right after a shift, when the RPMs were going down.
After priming and trying (and a whole lot of prayer) we finally got the truck started and were able to drive back home (100 miles from where this all started). I was able to take it to the dealership this morning and they are looking into it.
I'll post a picture of the fuel that came from the old filter later. Right now I'm thinking/hoping it's just a clogged line. I never had problems with it dieing (with this new filter) when accelerating, it was always on the deceleration that the truck would die out which leads me to believe that there is not enough fuel that is able to get to the engine without a lof of pressure behind it.
Anyways, just wanted to post an update in case somebody else ever runs into this. Will post pictures and final outcome later on.
09-07-2010, 09:11 PM #3
09-08-2010, 12:14 AM #4
Fuel lines can be a bitch, or be simple. From your description it does sound like a fuel issue. Have you gotten the truck ran through with a computer to monitor everything? Could be a faulty injector that you got replaced, or different injectors period. let us know how it goes. Fuel pressure regulator? Doesn't sound like its getting the right amount of fuel, or there's air in the fuel line still. Check your cockpit on the bottom and the top of the fuel filter. The top pit is a plastic screw, looks black, use a 1/2 wrench...it's plastic so don't strip it. If that doesn't work, then open the bottom one, then the top one and pump some fuel thru and then close it up and pump the manual primer until hard, it may take a few times. Good luck
Last edited by ippielb; 09-08-2010 at 12:19 AM.
2002 Chevrolet Silverado 1500 z71 1985 Chevrolet Silverado k10 2006 Chevrolet Silverado 2500hd 6.6l LLY Duramax 6.5" BDS Suspension Lift Key'd to 9" Edelbrock Carb & Polished Intake Manifold & Valve Covers NAPC Race Transmission & NAPC Built Transfer Case EFI Live Comp Cam and Valvetrain Snow Performance Methanol Injection 35" Toyo Open Country Mud Terrain on 18" Ion Alloy 179's Headman Long Tube Headers and True Dual Exhaust FASS 150gph Titanium Series Pump AirAid Cold Air Intake with K&N Dry Filter & AirAid PowerAid Throttle Body Spacer 2" Suspension Lift 33x12.50r15 Tires PPE Tuner until i tune it with my EFI Live Pacesetter Long Tube Headers with Cats Gone True Dual Exhaust FlowPro 3.73 Gears Yukon Grizzly Locker with Mag-Hytec Cover & Traction Bars NGK Iridium Tips & MSD Ignition Plug Wires Baja Spare Tire Holder Leveling kit & 34.5" Nitto Grapplers 18" XD Rims Innovate LC-1 Wideband o2 Sensor x2 HID's all around LED taillights and 3rd brake light BDS Dual Steering Stabilizers Pioneer Double-DIN Touchscreen Navigation with Two 10" Subs under rear seat Electric Fan Autometer Pressure, Boost, and Pyro Gauges 4.56 Gears AFE Stage 2 Intake
09-08-2010, 09:06 PM #5
Thanks for the advice. I will definately update. The truck is still at the dealership. I'll hopefully get a diagnosis tomorrow. They started looking at it right after lunch.
The fuel regulator was changed 3 weeks ago when the fuel injectors were replaced. The truck was running fine and the MPGs increased right after they were replaced.
It could be air. I had tightened the bottom bleed valve on the bottom and top, they both seemed to seal tight, but it's not guarantee that air may be seeping in. I did notice that the fuel filter was empty everytime after the truck would die. I'm hoping it's something as "simple" as the fuel lines and tank needing to be flushed. I don't know what the mechanics are doing to troubleshoot the problem so I don't know what all they are doing and how they are doing.
Will definately update tomorrow.
Thanks again for the advice.
09-09-2010, 04:32 PM #6
And the verdict is:
2 collapsed fuel lines. They said that both lines had been completely collapsed. They are ordering the new ones and will install them.
09-09-2010, 05:15 PM #7
glad they found the issue.David
2004 Silverado 2500 Crew Cab 4x4, AMSOIL EA air filter, Granatelli MAF sensor, Throttle body spacer, Magnaflow exhaust (true dual to 2 in 1 out muffler), 6" ProComp lift (add a leaf and 5" superlift rear block), Bilstein shocks, 35's (Cooper Disoverer ST) and 4.10 gears, Rhino Liner, EGRUSA fender Flares and widow visors, extended stainless steel brake lines, firestone airbags w/onboard air compressor, Pioneer Avic X940BT navigation, Accel backup camera.
1960 Land Rover Series II 88
2002 Nissan Altima (My Commuter)
2013 Toyota Avalon Limited (Wife's Car)
NRA Life Member
09-11-2010, 11:54 PM #8
I knew it sounded like a fuel issue, i'm glad it wasn't something major!
09-13-2010, 07:28 PM #9
Yeah, me too! Especially since I just replaced 4 injectors. I talked to the dealership today and the fuel lines have not come in yet (hoping they'll be there tomorrow), but they said that everything checked out on the computer when they first tested it out.
In the mean time I'm stuck driving my wife's Pathfinder (nice vehicle, but not very generous on head room if you are 6'2", lol).
09-17-2010, 08:50 PM #10
Finally got my truck back and everything is running great! They figured out that the guy that replaced the fuel filter when he changed out the fuel injectors didn't remove the plug on top of the filter and that is what caused all of these problems.
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