14 CFR §29.991

1. (a)Compliance with § 29.955 must not be jeopardized by failure of—
   1. (1)Any one pump except pumps that are approved and installed as parts of a type certificated engine; or
   2. (2)Any component required for pump operation except the engine served by that pump.
2. (b)The following fuel pump installation requirements apply:
   1. (1)When necessary to maintain the proper fuel pressure—
      1. (i)A connection must be provided to transmit the carburetor air intake static pressure to the proper fuel pump relief valve connection; and
      2. (ii)The gauge balance lines must be independently connected to the carburetor inlet pressure to avoid incorrect fuel pressure readings.
   2. (2)The installation of fuel pumps having seals or diaphragms that may leak must have means for draining leaking fuel.
   3. (3)Each drain line must discharge where it will not create a fire hazard.