Fuse Constantly Blowing

I have a 93 Pontiac Transport 3.8. Ok, I am a girl and know nothing about cars but here it goes... When you open my hood, On the left side hanging on what I call the support is a wire with a fuse on it. When I get in my van and it will not start, I can put a new 20 fuse in it and it starts right up. No one can tell me what this fuse goes to ????????? This morning, I am driving along and the van dies. I put a new fuse in it and it still won't start. It was towed to a shop and the mechanic is saying when he puts a new ingition module on it that it will srart and run but as soon as van is turned off then it pops this fuse? Does this sound familiar to anyone?? Thank You in advance for any help you can give me.....

Does your van have an aftermarket alarm or remote starter on it? I don't believe the fuse in question is a factory part, I believe it has something to do with and aftermarket alarm/remote start ignition kill

Well..although there is an legitimate "inline fuse" in that area as mentioned, the fact that it "hangs there" makes me consider Richtazz option as requiring thorough investigation, Toni...

..and that might explain that the fuse pops when turning the van OFF!! if that is really what happens. This would turn out to be a less costly repair job, if you can just have this suspect device disabled...