CIS Injection Filters

[rcdanly]

I'm in the process of cleaning out the fuel system in my 1977 930 because it sat unused to long and the fuel went bad. When I got to the fuel distributer I found under the injector line banjo bolts a very small screen type filter sitting in a recessed pocket. They are about 10mm long with a head diameter of 4mm.

What I discovered is that of the six filters in the distributer four had gotten up inside the banjo bolt and two of those had gotten to the point where the filter was being bypassed altogether. None of these filters appeared to be very dirty and I soaked them in carb cleaner. They seem to be fine, except I'm not sure what is going to prevent these filters from getting up inside the banjo bolt again.

My questions are: 1. Are these supposed to press into the fuel distributer which would indicate that mine have shrunk with age. 2. Am I missing some part that keeps these filters in place. 3. Does anyone know where replacement could be gotten.

Most parts guys that I've talk to don't know that these filters exist, and I've never seen them shown on any parts drawing. The person I talked to at Pelican Parts said he thought there is a Bosch CIS re-builder in the Los Angeles area, but could not come up with a contact number. He's the one that suggested I try here.

Anyone have any ideas.

THANKS
Bob Danly

[Gunter]

I know the filters exist but have not opened any banjo fitting to actually see them.
The CIS injectors also have a tiny filter-screen and I soak all 6 injectors completely submerged in injectore cleaner for at least 24 hours and then blow them out with air.

I'd clean out the whole system starting with the tank, pump, lines, accumulator, all lines to the FD, CSV and WUR, all lines to the injectors, soak injectors, flush out the FD, install new fuel filter.

There is also a tiny screen in the fitting on top of the WUR.

After a complete clean-out of the system and with a new fuel filter, I wouldn't worry too much about the screens inside the banjo fittings on the FD.

[rcdanly]

Thanks for your responce.

Are you saying that you would leave them out ?

[Gunter]

Maybe.

I might try and find any old used Bosch FD from that period mid to late 70's (Doesn't have to be turbo) open up and see how the screens look.

Aside from the screens, there are seals inside to consider. Best would be to have a rebuild FD from Bosch to be sure about new parts and calibration etc.

If you re-use as is, make sure the center plunger doesn't fall out while you're working on it. I believe you can lubricate the pivot for the Air Sensor Plate and then check/adjust the basic setting of the plate.

There are books for Bosch CIS available.

Make sure both pumps are working to get correct system pressure.
Re-assemble the CIS completely but do not insert the injectors into the intake runners. Instead, place the injectors into 6 equal-sized glass jars resting on top of the installed engine.

When everything is re-assembled and ready, fill the tank, leave the airfilter and cover off, turn the key to ignition ON (Not start) reach into the airbox and carefully lift the Air Sensor Plate for a few seconds to bleed the air out of the system. When lifting the plate, you should hear the injectors squeal and see fuel going into the jars.

This is how CIS is bled on NA 911's and should work on turbos?

You'll be able to see the spray pattern plus volume which should be the same in all jars if the CIS works correctly.

After the test, install the injectors, start the engine and see what happens.

Sometime later check Cold and Warm Control pressures to see if the WUR is working correctly.

[abed4d]

I can wholeheartedly recommend Larry Fletcher and his company CIS flow-tech in Alabama. His number is 251-929-3771. You can send him your FD and WUR and he'll make sure that they both work together as they should. Less than $500. I've used him numerous times over the years and never had to send anything back. He's also a real nice fellow that will take the time to help you.

CISFLOWTECH