How to Backflush a CIS Injector
 

I backflushed a CIS injector today using some of the techniques explained in Adrian Streather's book, "Porsche 911SC: The Essential Companion."

In the book (pages 294-296), Streather attributes the backflushing idea to Jim Williams.

Anyway, according to the book, to backflush an injector, you need to disassemble a bad injector to gain a spare pintle retainer that you then use to keep the injector being backflushed open.

I don't really have a spare injector to disassemble, so I made my own pintle retainer out of sheet brass with a notch for the center pintle pin. Put the injector that you're going to backflush in a vice. With very small pliers, gently pull the pintle pin of the injector out and slip the retaining collar under the pin's head.

I connected the injector tip (the lower end) to some clear plastic hose, clamped with a hose clamp. I then filled the hose with Berryman's (you have to work fast because with the pintle open the cleaner will just run on through the injector) and shot air through the hose at about 40 PSI.

I did this over a paper towel so I could see if any crud came out. None did.

I only did this with one injector. On all six, I again used the clear plastic hose, Berryman's and compressed air to check spray patterns, check for dripping, check for opening pressure, and hopefully, clean them a bit. They all looked good operating from the "right" direction.

Can you backflush an injector? Yes. However, I'm not convinced it accomplishes a whole lot.

Brian