Dealer not honoring warranty work..2018 5.3 Yukon issues

[Kpwweb]

The key to testing fuel pumps is LOAD. Go up (or accelerate up) a very long hill. Accelerate hard from a rolling start, etc... The engine needs to demand a large quantity of fuel at once (or a large amount over a long period of time). The other key for the fuel pumps is heat. Apparently there is a batch, or batches that fail under heat and load. Mine stumbled horribly with both those conditions. Would run fine normally--normal acceleration, etc. I did have a stumble every so often at idle, but would state the truck ran fine otherwise.

But when I floored the throttle one day--wham! The engine bucked violently AND THEN took off. I repeated the test and it did the same thing. Still accelerated normally under "normal" acceleration. So the best way to test it I found is in a safe place, roll at 5 mph and then floor the accelerator and hang on--see what it does.

 

[Bob2C]

Accelerated fine under conditions you stated above. No issues at all. So that rules out fuel I assume


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[swathdiver]

I did the fuel pressure test. Got it up to 50 from a dead stop. It didn’t drop. The low reading around 31 was idling in drive stopped. It fluctuated to 45. Do you think this is a fuel delivery problem?

Bob, I don't know how your fuel system works, meaning what pressures are normal depending on situation. Does someone here have the shop manual for a K2 and the DI motors?

 

[Tiredmechanic23]

Wonder if it could be in the high pressure system. A scanner that can read it would be needed. High pressure readings can be several thousand PSI.

I have seen a C7 stumble in certain conditions and they chased their tail on it replacing the in tank pump and the high pressure pump for it to end up being a check valve or something restricting flow.

 

[Bob2C]

Did some logging of high pressure. Also noticed low side dipped to 15psi while at idle in drive.

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[swathdiver]

Did some logging of high pressure. Also noticed low side dipped to 15psi while at idle in drive.

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Yeah, that's what I'd be looking for. So do these have a pump in the tank and another to increase pressure at the fuel rail? Kind of like a lift pump and an injector pump?

 

[Bob2C]

Yeah, that's what I'd be looking for. So do these have a pump in the tank and another to increase pressure at the fuel rail? Kind of like a lift pump and an injector pump?

Yes I believe they have both. My Kia gdi does.


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[Tiredmechanic23]

Yeah, that's what I'd be looking for. So do these have a pump in the tank and another to increase pressure at the fuel rail? Kind of like a lift pump and an injector pump?

Yup. High pressure pump is under the intake on the valley cover.

 

[smokey_mountain]

Bob and all please keep this research up, I am following this thread and I did not move away. I just have to do a ton of paperwork prep for tomorrow arbitration. As GM told me, "go ahead try arbitrage we will drown you in paperwork" they were not kidding...

 

[HiHoeSilver]

Bob and all please keep this research up, I am following this thread and I did not move away. I just have to do a ton of paperwork prep for tomorrow arbitration. As GM told me, "go ahead try arbitrage we will drown you in paperwork" they were not kidding...

They told you that? Smh. Let us know what happens!

 

[smokey_mountain]

GM loves arbitrage because it does not cost them anything, there are no risks for them and as Bob pointed out 90% of people will not go through that. I am at 112 pages of evidence at the moment. Had to substantiated every complaint with clear evidence per BBB rules. It is my payback to this excellent community - what is the value of arbitrage to car owners.

 

[smokey_mountain]

3-way pre-arbitrage call with BBB and GM Lemon Law team was not friendly at all. GM side was condescending, dismissive and disinterested. They said dealers looked into your car, we trust our dealers - no codes, no issues to repair. I asked what do I do now? Go to court or arbitrage? They responded by saying "do not threaten us with court, we will drown you in paperwork"... I chose arbitrage because BBB folks were genuinely helpful.

They told you that? Smh. Let us know what happens!

 

[Bob2C]

Just insane what your going through. I think the next car I get I will lease. Never had in my life, it’s more expensive, but after 2 or 3 years it’s gone. Just my opinion.


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[smokey_mountain]

The process of Arbitration is pretty brief, it is all based on the test drive with the Arbitrator if he can witness the problem or not. You have 5 mins to show the problem with him in the passenger seat. In my case the issue comes up stronger after I drive for 10-20 mins and engine fully warmed up. In 5 minutes around the block the transmission did not reach 180 degrees when I usually get the worst misses. Not sure if he felt it or not, I did. Judging by questions I was asked they wanted to know if car left me stranded or unable to drive. GM's position is that warranty does not cover minor shakes and vibration, they are normal and happen with all vehicles, they requested to deny the repairs.

 

[HiHoeSilver]

The process of Arbitration is pretty brief, it is all based on the test drive with the Arbitrator if he can witness the problem or not. You have 5 mins to show the problem with him in the passenger seat. In my case the issue comes up stronger after I drive for 10-20 mins and engine fully warmed up. In 5 minutes around the block the transmission did not reach 180 degrees when I usually get the worst misses. Not sure if he felt it or not, I did. Judging by questions I was asked they wanted to know if car left me stranded or unable to drive. GM's position is that warranty does not cover minor shakes and vibration, they are normal and happen with all vehicles, they requested to deny the repairs.

Didn't you have a chance to warm that thing up before the drive?

 

[smokey_mountain]

We waited for abitration to start for 35 minutes, then hearing went on for 50 mins and engine cooled off, then 5 mins drive and that was it.

Didn't you have a chance to warm that thing up before the drive?

 

[HiHoeSilver]

We waited for abitration to start for 35 minutes, then hearing went on for 50 mins and engine cooled off, then 5 mins drive and that was it.

That's crap.

 

[SnowDrifter]

Reading this thread is just... Sad.

How the mighty have fallen....

 

[Mighty Hd]

I think at this point I would just trade the thing in

 

[mikeyss]

Kinda makes me second guess buying another GM product in the future with how the OP has been treated by GM. They make big bucks from all of the new vehicles they sell, the least they could do is try and make him happy, or at the minimum refund the money he's sank into this vehicle. If GM attitude is that poor, I don't see the point in supporting them when it's time for a new vehicle. What ever happened to CUSTOMER first!