Sounds like the rotor is slapping the towers; pop the cap and look.
On second thought, that seems too tinny.
Second guess is the fuel pump arm not in continuous contact with the driver.
The towers are the contacts on the cap? I replaced the cap because those were worn down. Checking my replacement cap now it seems they are worn down again and it has only been 50 miles. Almost as if the rotor is too high.
