- 2012 Buick Verano
I had and issue with my 2012 Verano 2.4l flex fuel vehicle. After driving a while mostly when warm and I'd turn off the engine my car would still run for about five to 10 seconds basically dieseling or again would have pre ignition symptoms basically starting before I could finish cycling the key starting it. I also had a check engine light to accompany it. P0712 and 7E8 . P0712 was a fuel trim fault and 7E8 was a generic fault. I smoked test the vehicle . No leaks found. Checked plugs and everything else no problem. I met a GM master tech and he told me that the high pressure pump is more likely the problem. He explained that the plunger seal at the base of the plunger valve inside the plunger spring goes bad and fuel vapors and at times raw fuel gets by the seal into the engine crank case mixing with the oil and when the car is turned off especially when warm after driving a while that the engine continues to run after being turned off because theirs still a fuel source and it runs till its burned off. He said you're not going to get a fault code for a high pressure pump unless its and electrical issue with it and the fuel pressure readings will be normal on it. He said those high pressure pumps fail alot. Also he said you can also see a clean shiny base of the plunger valve where the fuel and vapors are coming through. Anyway. Bought and AC Delco high pressure pump online for $200.00 . Put it on and problem solved no more diesling/ run on after turning off engine or pre ignition. Hope this helps anyone out here with these symptoms.