A little over a week ago I concluded that I had a leak in one of the internal in-tank fuel lines on my Fatboy. Low fuel pressure at low rpm’s and visible cavitation when looking into the fuel tank. Removing the internals today, I discovered that the fuel lines were intact and that the cause of the fuel pressure loss was a blown “O” ring between the fuel regulator and regulator housing. I didn’t know this could happen! See Attachment.

Harley does not sell this “O” ring individually. Luckily I had a spare regulator which includes the “O” ring. Replaced the regulator, reinstalled the internals, and the problem was solved.

Harley recommends replacing the fuel filter on EFI models at 25,000 miles. It’s probably a good practice to also replace the regulator at the same time. The MSRP for the regulator is $40.00