Is there a problem with the car or is this preventative maintenence?
For maintenence I dump a bottle of Techron in the tank every oil change
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For a more concentrated cleaning, GM and others makes a top end cleaner that you hook up to the fuel rail. You disconnect the fuel pump inertia switch and run the engine on the cleaner. It wipes out the plugs so you will need to replace them afterwards.
Not this one again! Techron and Seafoam injector cleaners have petroleum distalates and are probably no harsher than lighter fluid. That is OK for every tank.
But if you want it really clean, use something that will take the hair out of your nostrils. B12 Chemtool has at least four strong thinners/cleaners in the ingredient list. It also must be kept in the metal can since when concentrated, it ate up the plastic bottles. It smells like the nasty stuff from the dealerships. And I try not to get it on my paint or skin. If a can of B12 does not help, you probably need to take off the nozzles for a manual flushing.