A fuel
system includes a fuel
injector having a split check
assembly with a control member, an outlet member, and a check sleeve. A trapped volume is formed within the check sleeve between the control member and the outlet member, hydraulically
coupling the control member to the outlet member. A start
rate shaping gap fluidly connects the trapped volume to a fuel cavity and is formed between the check sleeve and one of the control member or the outlet member received in the check sleeve, and regulates a start rate shape of
fuel injection from the fuel
injector. Related methods are disclosed.