2007 F150 4.6. I've had a strange pinging noise after I shut it off. Goes on pinging for 5 minutes or so. Sounds like it is coming from the front of the left cylinder. It's been doing this for at least a month. Now the other day my Check fuelcap appeared on the dash. I'm not sure if they are related but I would like to know what the problem is. Can you help

 

It sounds like it might be part of the emissions and vapor/evap system. See if you can get a read on any codes that might have been thrown. If you don't have a code reader, most auto parts stores will read them for free.

 

Thanks for the reply. I tried to save some money on a cheap locking fuel cap a few months ago That may be when the pinging started. A couple of weeks ago I bought a motorcraft locking cap off ebay but it's not exactly like the original. That's when the check fuelcap came on. I put the non-locking original back on and cleared the codes. So far so good. I'm not sure if that stopped the pinging. I will have to listen for it. I ride my bike to work when it doesn't rain so the truck get neglected. Thanks Mark