How do you help a team that is feeding turn the game around without dying to fed enemies?

Vision, objective focus, vision, choosing the right engagements, vision, and a little luck.

This is a great question because often times, if they are trolls, they will start screaming about you not "going in" or being a 'ream player" if they are the more civilized variety, or...

"you suck, ff" which is more typical of the low brow league troll community.

...if you try to help, they will scatter like cockroaches while you die.

I have no idea how I can constructively approach this issue.

You have to do what I call "baby sit" your teammates.
If you play top don't use your tp for lane but for bot-lane as about 80% of the time a game is won or lost from your bot-lane teammates. 2 bad players in 1 lane for an enemy adc it's a nightmare. So use your Tp for you team and not for yourself. You stats at the end of the game will not be pretty as for the most part getting to 200+ cs is difficult as your "babysitting" your team but you should be able to win more games because of it.

If your a laner and your team is behind go to the lane that is pushing towards your side and push it as fast as possible (not too far) but just push it back to the enemy. 1 or 2 of the enemy team members will go for the "free cs" at that point you need to make a move as your team has the small advantage of a 4v5/ 3v5. BUILD TANK if you are top don't worry about damage items unless you have already built damage items before the feeding happens at that point you might as well and finish what you started but after that build tank. The best way to do everyone's jobs are to be tanky enough to survive. The longer you stay alive to tank the more damage you will be putting out.

For example with full Ad/Ap is very deadly but in teamfights if you get killed early after only doing maybe a Q-E-W maybe get your ult off it's ok as you might do alot of damage but if your instead a Tank you can get multiple Silences off during fights that can win you the game.

Support you need to ward, most support players get so they don't get yelled at by their team but they don't ever use it. Be with your ADC at all times but DON'T be afraid to tell them what to do. Most times the adc player that has 7 kills and 0 deaths will get cocky and you need to tell them what to do. Remember most ADC players are more mechanical and no brain and are really the rage player of the group. Ping them when your about to ward etc.

MID most players that play mid think they need to roam 24/7 or if the enemy mid is gone they think they need to also roam. I personally do NOT roam as mid(most of the times) until I get the enemies mid tower. Getting the mid tower early is very good as most times the enemy mid will need to push back 2 waves if not more while trying to cs properly and having the risk of the other mid roaming. So the enemy mid will have to choose get the cs or help his team. Either way it's a win for you.

1. If he stays you will have 2v3 advantage at bot and THAT should be your first visit if you mid get the lane that has the MOST players in it AHEAD first. It also helps with getting dragon control early and often if you can also get the bot tower also. The enemy bot lane will have no choice but to cs afar or have the risk of running from their first tier tower(which is now Gone) and running all the way tho their 2nd tier to not die.

overall just be there with your team. I like to think of it like this. ALL the player that I play with SUCK and I need to CARRY however you can carry without needing to go 80-0.

I'm only S4 but thought my advice may help you in the future, GL and Have a Good One!

It depends on what stage of the game.

In the laning phase opting to group for a single tower and ending the laning phase can be beneficial if your team does well in team fights. After laning phase identifying whether your team should have a split pusher or try to win fights around objectives is a way. Trading objectives can be good, say give up dragon for a tower elsewhere, I don't suggest doing that with the elder dragon though. There's a lot of things you can do, you just mostly have to work together.

I will say that you shouldn't bother throwing out the "stop feeding" comment and "play safe" seems to be largely ineffective as well.

Depends on your position, champion, and your strength.

If you are in the top lane and your lane is "even" grouping may or may not help your team.

Say you play or any other split pusher.

You basically never group, get a zzrot and try to create map pressure. You will not win teamfights when your team is behind and if your team has adequate wave clear they should be OK.

I main and typically I avoid grouping if the other lanes are very strong and I am only "sort of strong". If I am the carry and the only one with kills, I group to help my team catch back up.

I have to make this decision a lot, because when my team is losing, me charging in their to help a weak team against strong opponents doesn't usually help after just one fight. Once the opposing team KNOWS that I am the only strong player on the team grouping is pointless they will just CC me and I will die.

How lopsided do the kills need to be for me to never group? Usually a 8-10 kill differential or more. Anything less than that (say 5) I will group more often to even out teamfights.

Map pressure is always the answer when all the lanes lost badly not grouping. You do not want to fight the opponents on their terms while they are strong.

You also need to play for picks.

Forget about kills, splitpush and get something done.