Well, if he didn't install an OEM fule pump, I would consider getting a new one from
http://www.everythinginfiniti.com (aka Joe - you'll see ).
Might call them and see if the float is available separately. Then get over to Infiniti Mechanic Forum and read Tangalora's excellent Fuel Pump Replacement post to see what he did wrong.
And even before that, you must read the Timing Chain guide post in the Infiniti Articles Forum.
Welcome to our resource.
Pull up a chair and start reading every post by Q45 tech a little each night for the next few weeks.