Vehicle Dies During Driving

[chandler583]

Hello all! I've got a peculiar problem I'm attempting to diagnose. I'm not super familiar with the LMG engine and I am out of my depth. I've got a 2012 Suburban with the 5.3L. It recently has gone through a lifter replacement and AFM delete and the associated programming that's supposed to be done with it. Now it will die out randomly when the vehicle is between 1/4 and 3/4 of a tank of gas. It will restart almost immediately after dying.

I'm leaning towards EVAP issue or A/F ratios, but I've replaced the entire EVAP system (valve, lines, charcoal canister). I have the ability to data log through a TopDon bluetooth dongle, but I'm not confident in deciphering the data that is logged. I'm about at my wit's end and all shops I spoke to are not able to help because they either don't have the time to diagnose an intermittent problem or don't have the technical knowledge to do so. Everyone local I've spoken to just suggest trading it in which is not really a solution in my opinion.

I'm looking for suggestions on what to look at/check for or any recommendations on who would be able to assist in hunting down this issue. I feel like it's something simple that I'm missing. I'm in the Houston area.

 

[Doubeleive]

I would start with a fuel pressure gauge stuck up in the hood/wiper area so you can see it while driving and monitor the pressure it should stay at or above 43psi at all times with engine running. key-on/engine off you should have 50+psi.
since there are no other driveability issues reported, that is where I would start.
you an buy a fuel pressure gauge kit at harbor freight for like $30, you don't need a $400 snap-on for this.

 

[Joseph Garcia]

Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

Pics of the truck, please. If we can't see it, it does not exist.

You are already receiving sage advice from the knowledgeable folks on this Forum.

Fuel, air, spark..... Start with those three, with the fuel pressure analysis being the first place to start.

You state that it dies 'randomly'. Give some hard though to this, to see if there is something, even small, that may be common to all of these failures.

 

[mikez71]

No codes?

Maybe tank level is coincidence? (less frequently above 3/4 or less than 1/4 tank?)
Since you've replaced all the evap parts, and a large leak should throw a code.. I don't think evap could cause a shutdown..

Maybe fuel pump or crank sensor starting to die?

 

[Fless]

Evap could cause a stall, at idle, if the purge valve is sticking open or improperly commanded open. That, however, should not cause this if rpms are above idle.

If this problem is at idle, I'd suspect a vacuum leak or a dirty throttle body (IAC).

Also I believe that you can watch the fuel rail pressure using a scanner that will display that PID.

 

[chandler583]

I do have some codes stored, but no MIL illuminated. Some of them may be set since they haven't run yet. I've attached the full report. I've replaced the purge valve since it was contaminated and stuck from charcoal migration through the EVAP system. I do get large negative fuel tank pressures around the time it dies out. I've attached a screen shot of the catalytic converter temps when it died most recently. It will die at idle, but it will stumble under load.

 

[mikez71]

Those just look like incomplete tests..

How much negative pressure?
Might unplug purge valve to see if it still happens..

 

[LsHart]

U should be able to drive around with the gas cap loose. And see if it does the cut off at what ever the level was. If it shuts off with cap loose its not evap. If it doesn't shut off then it is. Easy test to do for a runability issue.

 

[Doubeleive]

The only reason it might stall from the evap system is if the purge solenoid was stuck open and it was sucking fumes at idle (run rich). a stuck vent solenoid would cause refueling problems
if you did not use oem parts it could be the problem still. aftermarket tend to fail miserably

 

[Foxguy1973]

Hello all! I've got a peculiar problem I'm attempting to diagnose. I'm not super familiar with the LMG engine and I am out of my depth. I've got a 2012 Suburban with the 5.3L. It recently has gone through a lifter replacement and AFM delete and the associated programming that's supposed to be done with it. Now it will die out randomly when the vehicle is between 1/4 and 3/4 of a tank of gas. It will restart almost immediately after dying.

I'm leaning towards EVAP issue or A/F ratios, but I've replaced the entire EVAP system (valve, lines, charcoal canister). I have the ability to data log through a TopDon bluetooth dongle, but I'm not confident in deciphering the data that is logged. I'm about at my wit's end and all shops I spoke to are not able to help because they either don't have the time to diagnose an intermittent problem or don't have the technical knowledge to do so. Everyone local I've spoken to just suggest trading it in which is not really a solution in my opinion.

I'm looking for suggestions on what to look at/check for or any recommendations on who would be able to assist in hunting down this issue. I feel like it's something simple that I'm missing. I'm in the Houston area.

I would absolutely check the grounds on the firewall. I have a 2015 Tahoe LTZ that was experiencing the same issue, albeit with some other electrical issues. I replaced several electrical components (alternator, battery cables, etc) myself before finally submitting and taking it to the dealership I bought it from. They cleaned the grounds (I had no idea where they were), and I haven’t had the dying/restarting issue since. Just a suggestion…

 

[chandler583]

Thanks for all of the replies. The reported fuel pressure never dropped below 43 psi so far. It seems to only have this issue when between 3/4 and 1/4 of a tank. I'll keep keeping an eye on the fuel pressure when it's having issues. I've gone through all of the grounds chasing a separate electrical issue.

 

[kbuskill]

Thanks for all of the replies. The reported fuel pressure never dropped below 43 psi so far. It seems to only have this issue when between 3/4 and 1/4 of a tank. I'll keep keeping an eye on the fuel pressure when it's having issues. I've gone through all of the grounds chasing a separate electrical issue.

You said you replaced the purge solenoid due to charcoal pellets migrating through the system.

Did you blow compressed air from the purge solenoid line back towards the charcoal canister with the line disconnected at the canister?

If not, there is a very high likelihood that pellets will get sucked back into the new solenoid and hold it partially open. Also, the charcoal canister should be replaced if it hasn't been already.

This typically will throw a code for evap system leak and not really affect anything else but it could in theory cause rich fuel ratios and possibly stalling.

A good scanner hooked up and recording live data when this occurs would tell you a lot.