B737 flight crew reported engine continued to run even after fuel control was selected to cutoff.

Attributes
ACN	1699165
Time
Date	201911
Local Time Of Day	1201-1800
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Light	Daylight
Aircraft 1
Make Model Name	B737-700
Operating Under FAR Part	Part 121
Flight Phase	Parked
Flight Plan	IFR
Component
Aircraft Component	Powerplant Fuel Control
Person 1
Function	First Officer Pilot Not Flying
Qualification	Flight Crew Multiengine Flight Crew Air Transport Pilot (ATP) Flight Crew Instrument
Experience	Flight Crew Last 90 Days 491
Person 2
Function	Pilot Not Flying Captain
Qualification	Flight Crew Multiengine Flight Crew Instrument Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 284
Events
Anomaly	Aircraft Equipment Problem Critical Ground Event / Encounter Other / Unknown

Narrative:

Upon arrival in ZZZ; the captain shut down the engines and I ran my parking flow. Right about then the captain said that the ground crew was motioning that the number one engine was still running. I looked at the fuel levers and they were in cutout. I looked at the mfd (multi-function flight display) and sure enough; the left engine was still running. The captain wiggled the fuel lever until it shut off. He then wrote it up. Earlier in the day a ramp agent came to the cockpit in ZZZ1 to ask the captain if he had waited until the captain had given the engines cut hand signal before he gave the clear to enter signal because left engine was still turning after he gave the all clear. We assumed at the time the motor was just winding down; but after what happened in ZZZ; we couldn't help but wonder if the same thing might have happened; albeit briefly; in ZZZ1.we should have asked more specific questions to the ramp agent in ZZZ1 to make sure we knew what he was talking about instead of assuming.

Original NASA ASRS Text

Title: B737 flight crew reported engine continued to run even after fuel control was selected to cutoff.

Narrative: Upon arrival in ZZZ; the Captain shut down the engines and I ran my Parking Flow. Right about then the Captain said that the ground crew was motioning that the number one engine was still running. I looked at the fuel levers and they were in cutout. I looked at the MFD (Multi-Function Flight Display) and sure enough; the left engine was still running. The Captain wiggled the fuel lever until it shut off. He then wrote it up. Earlier in the day a Ramp Agent came to the cockpit in ZZZ1 to ask the Captain if he had waited until the Captain had given the engines cut hand signal before he gave the clear to enter signal because left engine was still turning after he gave the all clear. We assumed at the time the motor was just winding down; but after what happened in ZZZ; we couldn't help but wonder if the same thing might have happened; albeit briefly; in ZZZ1.We should have asked more specific questions to the Ramp Agent in ZZZ1 to make sure we knew what he was talking about instead of assuming.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.