2014 Silverado, 5.3 runs just fine until after filling the tank. Will start and run fine right after filling the tank. The next day turns over fine but runs super rough. It’s done this twice. The first time it quit on the way to the mechanic and started running fine. The second time got it to the shop while it was acting up. Mechanic said it was not sparking on cylinder 6 and had no compression on cylinder 8. Decided to take it to a dealer for warranty repairs, it started running fine on the way there and that shop could find nothing wrong with it. first time it did it we replaced spark wires and plugs. Made no difference in how it ran.
Any ideas would be appreciated. Thank you.

 

Take it to a car parts store or a friend who has an OBD II scanner and see if any codes show up, then post them here.

 

Might be an AFM problem. Is the check engine light on? How many miles are on the truck?

 

When it’s running rough, can you smell fuel as if it’s flooding?

Are you having any problems actually filling the tank (such as the pump keeps kicking off as if the tank is full even though it’s not full)?

 

Check engine light is only on when it’s running rough. Only code it’s know to have thrown was a 300 while it was running rough. When running smooth we’ve been told nothing shows up. No actual trouble filling the tank and it runs fine initially after filling. It’s after it sits over night or for several hours after. 72000 miles on the truck.
Thank you for any further information. Darn intermittent issues

 

Change the fuel filter, then go from there, IMO.

 

Drop some Techron or Seafoam in the tank along with some water remover.

 

The only fuel filter on that will be the sock on the fuel pump - there’s no inline filter.

It may be sucking liquid fuel through the charcoal canister or the purge valve is getting stuck open. Try disconnecting the purge valve line and capping the valve the next time you fill up and see if that makes a difference.

 

I'm really disappointed that Chevrolet deleted the inline fuel filters. I guess it was a cost-cutting measure. Cars, maybe, but the pickups, no.

 

It’s not just GM - except for LD diesel applications, most passenger vehicles now only have the pump mounted filter - it was different for each manufacturer but phasing them out started in the 2005-2010 range (at least for the US - I’m not sure about foreign makes).

Inline filters were necessary for carburetors and early FI systems but they do nothing to protect the pump. The filters on pumps today are capable of removing as much particle matter as any inline filter could - I don’t know what micron level they are off hand, but it’s as good as, if not better, than inline filters.

I’m not saying it’s fool proof, but nothing is. You can certainly add an inline filter if you wanted to, but I don’t really see the point when any particulates that could do harm are being removed before they enter the system.