loud tapping when trying to start after fixing hole in fuel tank

Someone decided to drill a hole in my truck's gas tank, presumably to steal gas, about two and a half weeks ago. After a lot of research I decided to use a Tech-Bond patch to repair it and it's now (hopefully) fixed.

Anyway, I filled the tank with 3 gallons of gas, and when I tried to start it today I heard a very loud tapping. I assumed it would take a bit to prime the system since it had been dry this whole time, but the loudness of the tapping sound, which seemed to be coming from under the hood, definitely surprised me.

Is this normal and just a case of cranking until the system is primed, or possibly a sign of a larger concern? Thanks.

 

This is one of those times where hearing the noise would help tremendously. I think many of us with the V8/4.7 have a tapping sound under the hood when running. Almost like a sewing machine.

 

Did they also try to get your cats? Check for exhaust leaks

 

Mine did the same after changing injectors

 

Okay, turns out I'm a dumbass - the battery was just a little low. Thanks for the view/replies, and apologies for the false alarm.