Jump to content

L8T dead on the highway 92k miles

lundimpact1775

By lundimpact1775
in 6.6L Gas V8 (L8T)

 Share

Recommended Posts

lundimpact1775 Enthusiast

lundimpact1775

Posted
Posted

Hi everyone. Heading home last Thursday from running some errands my 2020 L8T went into limp mode and then died while cruising 70mph. 

 

As I waited for a flatbed I attempted some starts, which resulted in crank crank Frank no start. 

 

Codes showing immediately at limp mode were p0089, p0304 and p228c. I'm hoping it's "just" the hpfp, but any input is appreciated and welcome. This is based on the p0089 and p228c faults, combined with the no start condition but I'm only guesstimating here.

 

Current shop status is that every light on the dash is now lit up and they were able to start it but it misfired badly. Hope to have a final diagnosis later today.

  • Sad 1
lundimpact1775 Enthusiast

lundimpact1775

Posted
  • Author
Posted

Multiple stuck injectors and a failed high pressure fuel pump is the final verdict. 

 

I'm just astonished that those things could all fail spectacularly at once. Would have guessed one or the other. 

Pryme Senior Enthusiast

Pryme

Posted
Posted
25 minutes ago, lundimpact1775 said:

Multiple stuck injectors and a failed high pressure fuel pump is the final verdict. 

 

I'm just astonished that those things could all fail spectacularly at once. Would have guessed one or the other. 

Yeah that does seem odd. How many miles on your truck?

lundimpact1775 Enthusiast

lundimpact1775

Posted
  • Author
Posted

92k and some change on the clock.

 

Bought it at 89k from a known reputable dealer. Needed something reliable with a crew cab and the normal size box, and did not want to break the bank. Hence buying a pre-owned unit with higher miles. 

 

My favorite and most reliable truck I ever owned was my 2010 1500 with 6.2 I bought it with 120k on the clock in 2013 which is very high for its age. Drove it until 2019 and 265k miles without a single hiccup. 

lundimpact1775 Enthusiast

lundimpact1775

Posted
  • Author
Posted

I suppose that makes sense, hadn't considered it that way.

 

We are replacing all 8 injectors anyway, and plugs since it's coming due soon. Should be all taken care of this week. I hate paying shop prices... But at this stage in my life I guess I can afford it and I probably would not have caught the failed injectors until after it was all back together. I did guesstimate the hpfp correctly anyway so that was worth a grin.

64BAwagon Senior Enthusiast

64BAwagon

Posted
Posted

My sons 5.3 went at about the same miles. Had to drop the tank also and replace the pump in the tank as well as clean it and flush all the lines. One of the lines at the HPFP is one time use and must also be replaced. 

newdude Senior Enthusiast

newdude

Posted
Posted
18 hours ago, 64BAwagon said:

When the HPFP goes it spreads debris through the system much like when a CP4 grenades. 

 

 

Gas are returnless fuel system.  Diesel are still a return system which is why the entire fuel system on a diesel ends up with metal. 

 

Only place for the metal to go on a currnet gas truck is into the high pressure lines and the injectors.  

64BAwagon Senior Enthusiast

64BAwagon

Posted
Posted
1 hour ago, newdude said:

 

 

Gas are returnless fuel system.  Diesel are still a return system which is why the entire fuel system on a diesel ends up with metal. 

 

Only place for the metal to go on a currnet gas truck is into the high pressure lines and the injectors.  

 It was a 2014. I know he pulled the tank and pump also. Thanks for clarifying that. 

newdude Senior Enthusiast

newdude

Posted
Posted (edited)
18 minutes ago, 64BAwagon said:

 It was a 2014. I know he pulled the tank and pump also. Thanks for clarifying that. 

 

 

Gotcha.  GM went returnless back in 2004 on trucks so I should have clarified that lol.   

Edited by newdude
lundimpact1775 Enthusiast

lundimpact1775

Posted
  • Author
Posted

Well here's an update for anyone interested, picked up truck Thursday, 40 miles home. Drove it into town to gas up Friday morning, then headed out Saturday morning for a 250 mile road trip with a truck full of people. Stopped for lunch at mile 200, ate, hit the road. 55mpg cruising, same exact failure.

 

Towed back to the shop that fixed it (luckily, passenger had AAA with 200 miles range). 

 

They offered a free loaner which I declined as I have a car too. They dissected it first thing Monday morning and said the new hpfp they installed had an internal fault in the regulator, causing it to misbehave. Another new hpfp in and picking up again tomorrow. 

 

I've lost so much confidence in my "road trip" rig at this point... Idk what to even do though besides keep driving it since this work is all under full warranty for 2 yrs/ 24k miles. My only solace at this point is the shop in question has committed to ensuring it stays on the road under their warranty. 

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing

  • Latest Articles

  • Posts

    • Paul8556
      Headlight issue...

      By Paul8556 · Posted

      Did you ever find a resolution to this? my 2019 Silverado 1500 is showing the exact same headlights issues with the exact same symptoms.  would help a ton if anyone has any advice on this or better yet a known solution..
    • RyanbabZ71
      Gas Prices

      By RyanbabZ71 · Posted

      Wawa and Meijer here have ethanol free (88 & 89) I use for my mower and lawn equipment.  Its not much more than reg.  I paid $3.29 a few weeks ago.  
    • Atlas
      Wow I'm in a pickle. (Broke down truck) and a story.

      By Atlas · Posted

      tl; dr I've now reached the 6th floor of hell. I'm chronicling my journey for my morning readers.   Pulling the top of the intake apart was moderately easy but it involved a lot of parts, connections, and minutae. I was preparing for the new fuel lines to arrive ("nut and bolt kit" it's called). The fuel line connections are notched and held in place by the manifold and a metal plate with a T27 screw.   It's on the back of the intake, under the firewall, with little clearance, and two hard metal fuel lines in the way. I was using Franken-tools (weird combinations of 1/4 inch ratchet with/without an extension, with a bit holder for my T27) to get in there. One of my sockets and bits fell off and has yet to emerge on the floor. I lost a second setup and that's when I almost started throwing tools. But that was the point at which I had gotten traction on the Torx head, and it promptly stripped. No more traction.   I started humming "1-877-kars-4-kids" because I was about at that point. You know what? I'm $1500 into this thing and I can make it disappear just as quickly. This isn't fun anymore. I had spent a lot of time already "tidying" around the engine bay: Fixing all the "someone's been here before!" BS. The truck has been exclusively dealer- and shop- serviced and I'm reminded of why I never let other people work on my cars unless absolutely necessary.   Speaking of dealer service. This truck has a 1" stack of records going back to 1995. I put them all in an excel spreadsheet, date/mileage/description.   The CPI spider has been replaced 4 times in 85k miles. The EGR? Another 4. Multiple, multiple O2 sensors. One Cat. 4? Sets of plugs and wires, and I swear half the stack is diagnosis paperwork for "misfire, runs rough, extended crank, dies at stoplights".   GM was producing some proper crap back then. And it was still well within the era of brittle/crappy plastic. (Windows 95 was released the same month this truck was sold new, we HAD the technology!!)   There (was) a plastic shroud around the evaporator core and HVAC fan in the engine bay. I noticed a chunk of it missing so I poked at it some more and it literally shattered. Touched it some more and pieces were crumbling off. Had a good laugh. Clearly whatever plastic garbage they were using had broken down over 30 years and was literally turning to dust. That was a good half hour of using a shop vac to remove the rest of it.   Back to it.   I was going to give up for the evening but then decided I'm already level 10 pissed off at the stripped screw: G* D* it, give me my tools back -- and my JOY. We'll do this the hard way: The whole intake is coming off.   Blazer won Round II. After finally finding and accessing the 12 intake bolts and using a pry bar to unseat it from the heads, it popped loose in an explosion of gunk and grime raining down into open ports. Awesome.   6 times I reminded myself: Be careful of the temperature sender on the front of the intake.   YEAH, I forgot again and snapped it clean off in the removal. Add another $20 to the ever-growing list of new parts this thing is consuming.   The shame is, long before removing the intake, I had changed the oil in prep for Tuesday's momentous fuel line replacement that was going to be the magic fix and I'd have a running Blazer to tool around in this next weekend. The intake removal, including raining gunk, also gushed dirty coolant all over the valley. Of course it did. Welp, there goes another $35.   I now need an intake gasket set, bolt set, coolant temp sensor, another 5 quarts of oil, some RTV. Don't worry, I've already got 3 new jugs of Dexcool and a thermostat waiting. I'll fill it with clean water first to get it running, dump it, and then add the Dex later on in case... well, let's not go there. I'm only tearing this down once, next time the truck is going on Marketplace for FREE.   Oh, and I'm going to need vacuum hose for all the stupid connections placed at the rear of the engine which have since disintegrated. Come on, GM....tell me you don't do that anymore?   Oh, and the ears on the distributor where the cap screws down are both cracked. I mean, why not put a new distributor in it too. You get a distributor, YOU get a distributor, Everyone gets a new distributor!   This truck isn't out of the woods yet...I'm already questioning how much more time I'm willing to sink in.
    • William Aldrich
      Bent valve in 2025 GMC Canyon Denali - Requires engine swap at 14K miles

      By William Aldrich · Posted

      NewDude, thank you for the suggestions!    I did follow up and the dealer indicates he has an open CX case and is working with DPAC (Dealer Parts Assistance Center).   Per the dealer, GM has had a quality spill and is not providing an update for when a replacement engine will be available.
    • Silver Yeti
      Poll: Does your truck have the rear window leak?

      By Silver Yeti · Posted

      That's interesting.   There was a factory wire-hole in the back, top of the rear cab, which had a wire for the third brakelight assembly running through it, as well as several holes (10 of them I believe) for all of the studs coming off of the 3rd brakelight assembly itself.   I sealed all of those holes with RTV/silicone as well.   I found it kind of odd, that none of those holes, were sealed with any kind of sealant by the factory - if there was any there, it wasn't very much.   That said, I've been out in heavy rain and have ran the truck through high-pressure car-washes a few times now and she has been 100% water-tight to this point.   I feel very confident in the repair, we'll see how it holds up.

  • GM-Trucks.com Clubs

  • Popular Contributors

×
×
  • Create New...