L8T dead on the highway 92k miles

lundimpact1775 · September 30

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.

Pryme · September 30

Keep us posted. Hopefully it’s nothing super serious.

@newdude should be able to give you info on those codes.

Edited September 30 by Pryme

lundimpact1775 · September 30

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 · September 30

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 · September 30

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.

64BAwagon · September 30

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

lundimpact1775 · October 1

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 · October 1

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.

sno1 · October 1

I wonder if adding a lubricant to the fuel would extend the life of these pumps?

Something like Lucas Oil Complete Fuel Treatment, Marvel Mystery Oil, or Sea Foam?

https://www.lucasoil.com/product/fuel-treatments/

https://marvelmysteryoil.com/products/marvel-mystery-oil

https://seafoamworks.com/sea-foam-motor-treatment-oil-fuel-additive/

newdude · October 1

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 · October 1

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 · October 1

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 October 1 by newdude

64BAwagon · October 1

Thats when the gasoline fuel filters went away, Right ?

lundimpact1775 · October 1

Having a known reputable shop take care of it. Sure isn't cheap but I trust their work and how thorough they are.

lundimpact1775 · October 9

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.