A cup of kerosene in a tank of fuel shouldn't cause any problems but injector cleaner is not simply kerosene. Injector cleaner contains a number of specific detergents, solvents and other compounds designed to do specific things within a vehicles fuel system without causing damage.
If injector cleaner was simply kerosene, such an 'industrial secret' would have become common knowledge by now and every man and his dog would be using it instead of purchasing injector cleaner at some silly markup (making stocking the stuff a mute point for businesses).
From what i have read, the major component of what is considered the quality injector cleaner is polyetheramine (PEA). This stuff is meant to be the most effective detergents at removing carbon deposits from within the combustion chamber and elsewhere. It was patented by Chevron in the early '80's and they called it
Techron. Chevron included it within their petrol pumps at 400ppm, yep ppm. Down under, Shell advertises its premium unleaded as having great cleaning proporties so i'd guess they also add Techron to their petrol mix (bucket chemistry as you call it). I'd think the patents would have expired by now which I guess is why there are so many brands of injector cleaners on the market.
May be Techron is cheap to buy if you know where to get it from and happy to buy it in commercial quantities (44 gallon drums?). But mixing it at the correct % so as not to cause issue could be challenging. Keep in mind that chemicals at differing concentrations can have differing characteristics and thus impact components within a vehicle. As an example, coolant (dexcool) has been known to cause softening of some plastics/rubbers and it took GM some time (and a class action) to resolve that issue by changing the formulation of dexcool
Unless you're actually a chemist, it might as well be rocket science
And from a fuel system perspective, it's not just carbon deposits that cause issues within a vehicle. Petrol can also cause gummy varnish deposits outside the combustion chamber; in tanks, fuel bowles and fuel lines, not just in injectors. As an example, my motorcycle's float bowl had lots of yellow varnish within the carburator which made the engine run like a dog. Such deposits were a pain to clean off and kerosine did a rather poor job at cleaning the dismantled parts. Being years ago, can't remember what chemical I ended up using to wash the crap off but it was done using elbow grease on the dismantled carby parts. I'm sure there is a specific chemical additive that will wash such varnish away when mixed to petrol but living well with the various plastics used in modern vehicles tanks, lines and injectors is the challenge for the chemists. Heck Boch injectors have issues in our LS3's simply trying to cope with petrol and those guys spend millions or R&D
So I hardly think a backyard 'cook' can be certain what they make will work efficiently and will be safe over the long term for all the plastics as used in a modern vehicle
So feel free to pour a cup of kero in your tank, maybe add some metho as well to allow the water to mix with the petrol so it can be consumed. It shouldn't cause any real issues, shouldn't. But I doubt it will clean anywhere like the 'engineered' injector cleaners containing PEA
Me, i'll let the oil companies do the chemical engineering work with additives in petrol as i usually don't add injector cleaner to my car. Somtimes on the rare occassions, when its on special, i'll buy some stuff and chuck it in a tank, usually I don't bother with additives.
