Should I use fuel injector cleaner on my 79 Volkswagen

a 79 probably won't have fuel injectors if you want to clean out the system use fuel line cleaner instead and only use it if you know the lines have something gummed up in them

It is fuel injected

well you can use it if you want to but it can sometimes cause your engine to go threw a lot more gas then is normal for a long while so i would suggest using it on maybe half a tank of gas and wait till it pretty close to empty before refill

I think i have dirty or bad gas in my 77 vw super beetle , but how would a extreme novice like me , know if its gummed up