slow starts

[ohiochica]

ok i have a problem and my bf says i am crazy but i know its a legit problem! my civic starts absolutely fine when i have half a tank of gas or more but the minute it drops to below half tank it has to crank longer to start. it gets worse the lower the gas is. butttttttttt here's the tricky part if it is still warm no matter how low the gas is it will start fine and quick. he says i am imagining it but i am not! it happened this summer and winter. help!!!! what do i make him check? he is a honda tech so he should know but he is refusing to even look at it. grrrrrrrrr