Injection Pump Solenoids Bosch 0330101013 0330101012

[Fonzi]

I am trying to learn and understand the r20y injection pumps (from 1969 280se) I have here, and would like to understand what the top solenoid (Bosch 0330101012 ) and bottom solenoid ( Bosch 0330101013 ) are supposed to do. 

The pump that was in the parts car with good compression seems to have a bad check valve on cyl 4 but I wonder if it has other issues as I note the solenoids have definitely been off and make even broken.  See the bottom solenoid in the background of the picture.

[mrfatboy]

Top solenoid is for fuel enrichment in the FIP. I pushest the rack forward. It always engages when starting the car cold or hot.

The bottom is called the fuel cut off solenoid. It is engaged by a micro switches on the firewall and transmission when at idle and 3 or 4th gear I believe. In don’t remember exactly. It was designed to cut down on air pollution.

You can read about it more in the tech manual.

[Fonzi]

Thank you!  So I should get 12v to the top one when cranking.  Should 12v continue after I let off the starter?

I’m thinking I should leave the bottom disconnected when trying to get an old motor running.  Eh?

[mrfatboy]

Yes. You should get 12v on top solenoid only when cranking.

Some people disconnect none, one,  or both depending on their particular issue.

[Fonzi]

Thank you! 

Just curious, after cranking, what handles the enrichment while the car is warming up?  Is there a wax bulb up top that somehow affects the amount of fuel that goes to the injectors?

[mrfatboy]

Correct. Do a search on “WRD” or Warm Running Device. Check out the tech manual. All the answers are there👍👍