Front Derailleur not shifting up

[Skyguy9999]

I've been trying to get a front derailleur (Shimano with index shifting?) adjusted. I got the cable tightened, and been trying to get the adjustments down. It can shift down okay, but it won't shift up to the next chain ring unless I hold the shifter down between the next set of gears. The chain seems stable when I do that in shifting and does not fall off the chain rings in either direction (towards the frame or the pedals).
I centered the frame with the L screw, but I've had the H screw anywhere from all the way in to all the way out to no effect. I've even tried moving the frame around, but still not getting what I need.
So, what needs to be done, so the derailleur will function in shifting up to the next gear without manipulating it as I described?

[Alex Ramon]

The 'H' screw is only there to make sure the chain doesn't go to far and fall into your pedals. The 'L' screw makes sure the chain doesn't fall into your frame. Neither of those screws will help with the actual shifting adjustment. The shifting adjustment is all managed by your cable tension and derailleur angle.
It sounds like you'll need to pull the cable a little tighter to get it to shift up. If that effects your down-shift then it may be a problem with the angle of the derailleur. Make sure the outer cage of the derailleur is parallel with the large chainring (check <a href="http://bikeride.com/adjust-front-derailer/">this video</a> at about 0:55) and then adjust the cable tension again.

[Skyguy9999]

Thanks for the help and for the resources on this site! I ended up moving the derailleur angle and tightened the cable tension using a pair of vice grips (best tool I had on hand for it outside of my hands) and got it so it works about 80-90% of the time now. So I guess it's close enough now that I should be able to get it with some minor adjustments.
Thanks again!