For some reason I am getting hurtburn while I run. I mostly get it when I am going up hills and when I come down it goes away. Does it have something to do with my breathing or does it have to do with how hard I am pushing myself? I am waiting 1 to 1 1/2 hours before I run to let my stomach settle after eating. So what could it be? Help!!!!
Two suggestions. Maybe 1 to 1 1/2 hrs isn't long enough to wait before running (depending on what you last ate and when how hard you are running).  Also, watch your posture while running. Typically people crouch over and lean into the hill when they are running uphill. Then when they run down hill, they run upright. Since you are saying it happens when you go uphill, my guess is that poor uphill posture is triggering the heartburn (probably also doesn't help clear breathing either).
Eating oranges (or orange) juice before a run can make this worse, but...
I think this could be partly psychological stress from challenging yourself, especially which looking up the hill - I used to get this, and I would say that I am pretty amazed at the way the mind can affect the body.
I now culivate a very positive attitude all the way around my run, and it has a big impact on how I feel, aches and pains go away quickly, less stomach problems and quicker recovery times between runs. I also get a very good high now at about 1 to 1:30hrs
Try forcing a smile, think more happy thoughts, imaging an invisible force pulling you up the hill (I.e the run is "just happening", not you doing it) think about times you have been generous, pleasant times in the past, holiday plans... that kind of stuff.
I'd be interested to see if this makes any difference.
For me it really depends on what I eat before. If I have a healthily lunch, eg, salad or reasonably sized sandwich I can run very safely after 2 hours. But anything big, greasy or worst of all spicy and or acidic! I have issues with heart burn even if I wait up to 5-6 hours later. I've learned to just live with out the super-sized spicy burritos in my diet, and personally I think that I'm much better off for it.
I have learned (the hard way) to wait at least 1 1/2 hours after I eat to run. No burritos, tacos, fried anything, acidic fruit juices or carbonated drinks. I pretty much have a fool proof pre-run staple. Slice of whole wheat toast with peanut butter, banana and glass of water. That is pretty much it. I can safely eat any type of pasta or baked chicken a few hours before hand, but nothing spicy. Personally I have more of an issue with side stiches. I haven't found a clear answer as to why those happen...
Running often makes me 'burp' - and occasionally I get some acid too. I think the burping comes from swallowing air somehow - and the acid comes from the burping.
Don't know of a remedy other than what people have already suggested above....Â