throttle body ignition question

[hjs]

hi,
i have an 87 chevy c10 with a 350 and throttle body ignition. on cold starts the motor has to turn over four or five times before it actually starts. warm starts it fires right up. the motor runs well otherwise. it's got 120,000 miles.
the throttle body has been rebuilt and i installed a rebuild kit. i was wondering if this cranking problem could be a caused by a leaky check valve. does the fuel pump have a check valve built in? should i consider installing a new fuel pump?
thanks