Early car cold start problem

[Mike M]

Hello...Lately, my 69S has been hard to start cold. There are 2 sending units on the breather cover. The one closest to the back of the car,with a yellow wire, I think is the culprit. There is power to the sender. Question is, what does that sending unit do?
The engine cranks and cranks for quite a long time before it starts, and I have tried all kinds of combinations of hand throttle and gas pedal.
Am I on the right track? Anything else to check?
Early S Man????
TIA

[Rot 911]

Do you still have MFI? If so sounds like you have either lost power to your cold start enrichment solenoid or the enrichment solenoid has gone bad.

[Early_S_Man]

Mike,

The cold-start circuit on the '69 911E and 911S models is a bit more complicated than 1970 and later models!

The two-pole 'sender' with the 'G' and 'W' terminals is called a 'Thermo-Time Switch' ... and there are two of them!

The Yellow wire is the same as the #50 starter solenoid lead from the ignition switch, and goes to the 'G' terminal, which is a heating element with about 25 Ohms resistance to ground, the body of the sender. The Yellow wire is 'multipled' over to the 'start assist' switch.

The Red/Black or Red wire goes to terminal 'W' and is the switch contact. When the switch body is below about 112°F, the switch contact should be closed to ground. The Thermo-Time Switches can be removed from the breather cover, and tested in a pan of water on a hotplate.

The Key below refers to Device numbers on the schematic that are numbers inside circles adjacent to the item. The devices of interest in the cold-start circuit are #68 Cold-start Solenoid, #66 & #67relays, #70 Time-Limit Switch, and #71 & #72 Thermo-Time Switches.

[Rot 911]

Originally posted by Early_S_Man
Mike,

The cold-start circuit on the '69 911E and 911S models is a bit more complicated than 1970 and later models!

Mike, Warren is correct. I just know enough to be dangerous!