I once wrote a story with first person, past tense narrative. I thought it was pretty good. Beta readers thought it was better than okay, but felt something was amiss. I was fortunate to have a writing instructor look at it. He spotted several core issues, but the one that pertains to your problem is, in part, this:
... the entire story is told in past tense, first person. This eliminates the reader's sense that the protagonist can be threatened with mortal danger.
A large problem with first person narrative, is that the action is all off stage. I.e.: the narrator is recounting events that occured to her in the past (in retrospective, as it were) and she can only recount those events she witnesses. All else is hearsay.
First person narratives (and some tight third person stories, as well) also tend to have problems with info dumps. This is especially true if the world is, by design, unfamiliar to the reader (an alien planet, another dimension, etc). In third person, the author can "show" considerably more about such a world than he can when the narration is limited to the point of view of a single character (first person). First person works nicely when the action takes place in familiar territory (Los Angeles, Miami, Moscow, a sailboat in the Pacific, etc.). But things slow down then the narrator has to pause frequently to inform the reader about the place(s) where events occur.
Oh, yeah. My story? I recast it in third person past tense, followed some of my instructor's advice and it is vastly improved. It's currently being shopped--we shall see if the advice and rewrite worked as promised.
