Searched around on the site, but couldn't find much on cleaning the CIS motor on a Regina '90 740, though I seem to recall a short thread about this awhile back, where somebody sprayed several changes of carb cleaner inside, shaking and draining between applications. Unlike the earlier Bosch, this type of CIS motor, VDO 1389557, doesn't seem likely to disassemble. I don't want to damage any internal components. Anybody cleaned one successfully? Thanks!

I successfully cleaned my Regina CIS a couple weeks ago. In my case I was getting a trouble code, and an occasional hard/stumbling start. First, I removed the unit from the car, and ran carb cleaner into both ends, shook, and drained. Then I hooked up 12 volts to the terminals and ran the plunger back and forth a few times, more carb cleaner, more 12 volts, etc. until the carb cleaner came out clean. Reinstalled and now works great. No trouble codes and no hard/stumbling starts.

The regina cis is different than the bosch in that the bosch is a motor that opens/closes a valve whereas the regina is a solenoid-operated plunger thingy.

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Matt L. -- Cary, NC -- '91 740 wagon

Thanks for your excellent answer, Matt. Sounds to me as if the Regina/VDO's relative simplicity makes it easier to clean successfully. Will try it and report.