74 cis 911 cold start woes

[dickranm]

When trying to start the 1974 911 cis cold I always run into problems. I need turn the key to engage the fuel pump, wait 15-30 seconds, then I pull up on the “Throttle” lever to engage the cold start valve…wait 30-45 seconds…..THEN turn the key the rest of the way and still it could take 2 or 3 try’s to get the car to start….and she then sputters to life. Thereafter, for the rest of the day she starts right up, no problems…jut that initial start up after she sits over night.

Any insights, similar experiences?

This has occurred since I’ve owned her (7 years). My mechanic in NY could never find anything wrong, he said it was kind of normal for these cis cars without a dme. He would always check the cold start valve and it seems to function normally.



Dick M.

1974 911

1987 951

[vash]

that lever doenst have anything to do with the CSV. it does the same as partially holding the throttle down with your foot. my CIS car starts right up with a bump of the key.

testing the CSV isnt fun...it is way back there. are those two wires that attach to the thermovalve (looks like a sensor on the drivers side cam chain cover) hooked up?

[HarryD]

Originally posted by vash
that lever doenst have anything to do with the CSV. it does the same as partially holding the throttle down with your foot. my CIS car starts right up with a bump of the key.

testing the CSV isnt fun...it is way back there. are those two wires that attach to the thermovalve (looks like a sensor on the drivers side cam chain cover) hooked up?

Vash,

I believe you are incorrect. They way my 1973.5 CIS is wired, the cold start valve will only work when the hand throttle is open AND you are cranking the car.

If you look at the electrical diagram below, #2 is the Starter motor, #12 is the cold start valve, and #14 is the microswitch on the throttle body that gets activated when you pull up the hand throttle. You will note that the yellow wire (cranking signal from the ignition switch) goes through the cold start valce and to the switch and then to ground.

[azasadny]

My '74 with CIS never started easily when "cold" and I replaced every component in the CIS until we determined it was the fuel distributor. There are many things to check and there are alot of good threads to help you out here. CSV, WUR, Thermotime switch, throttle microswitch, etc... are all components that need to be tested. Get a pressure testing kit for the Bosch K-Jetronic FI and follow the instructions. Remember that your CIS is 33 years old and a little "crankiness" is to be expected... Good luck and let me know if you need any spare parts for your CIS, I've got everything except a good fuel distributor.

[coolngroovy]

I've got the same problems, but i dont know where to start.
Following this thread with great enthusiasm.
Where again is the cold start valve?

[Jim Sims]

Follow the below thread to others that discuss this topic:

Fuel distributor and cold start issue link???

[coolngroovy]

Thankyou Jim, just what i needed.
One more Q, Where is the throttle lever?

[Jim Sims]

If the car has one, it will be between the seats; I recall that only the 1973.5 T and 1974 have the lever but some 1975's may have them too. What year of 911 do you have?

[coolngroovy]

Mine is a 74. Is it the lever with the red handle?
I thought that was for the heater?

[Jim Sims]

The throttle handle is black (heater handle is red) and should be the left most of the two handles in a LH drive car; if you have a RH drive car it may be the right most handle.

[PRE-H20]

i have a 74 fuel distributor that i didnt use if anyone is interested.

i was having fuel issues, i bought this fuel distributor. but i never used it, i ended up replacing the whole engine rather than hunting down a fuel gremlin. looking at 1500 bones for a FD was enough to go with a whole new engine and just be sure.

now i am a happy man. i start up with a roar in about half a second. mine is also the beloved 1974 911!

so if anyone wants a fuel distributor please let me know as it is just sitting here......

[ventana]

After completely rebuilding my ‘74 911 with CIS my mechanic still had a problem with reliable cold starting. The CSV would not consistently work even though juice was flowing to it. We reasoned that the 33-year-old wiring was probably at fault. He installed a rubber-covered toggle switch on the dash just to the right of the steering wheel and wired it to engage the CSV only when the ignition switch is in the on position (key turned all the way to the right). Much the same as you see in the wiring diagram shown above and kindly provided by Harry D. Problem was solved. My 74 starts every time first time using following procedure: Turn key so pump is running, pull up the manual throttle lever until it stops, press the new toggle switch and turn the key to engage the starter. When starting the engine after it warms up pressing the toggle is not necessary. Just to test the system I started my Coupe last month when the temperature was 5 degrees F. outside. It fired on the first try.

[Sunroof]

The '74 was the first with the thermotime switch that came after the 73.5T CIS. I was not aware that the 74 had a hand throttle for cold start up! I went throughthe same problems you are incountering and its a mess sometimes. Fuel pump check valve? Warm-up regulator? Improper mixture setting? Fuel Distributor? Cold Start Valve? Thermotime switch (74)? and on it goes...... If its sputtering to life you may want to first check the mixture setting and the fuel pressures. I replaced my warm-up regulator and the damn thing came back to life!
Do not pump a bunch of $$$$ into new components without going thru the testing. Your mechanic can run the fuel pressures and compare them to what is required. It can be something as simple as a dirty sensor plate, dirty injectors or that infamous fuel pump check valve. Keep plugging away, use this board for assitance and your get it resolved.

Bob
73.5T

[vash]

wow, sorry for the crap info...learned something new...

[HarryD]

Originally posted by vash
wow, sorry for the crap info...learned something new...

Vash,

Your info is not really crap. It is correct for your '81 which has automated the hand throttle thing.

[coolngroovy]

Well i'll be buggered! I just went & had another look. Guess what i found Jim?
So do i pull this lever up to cold start, then push it down when it fires?
I've got the car on ramps atm, it will probably be 2 weeks before it comes down. I cant wait to try this!

[HarryD]

Originally posted by coolngroovy
Well i'll be buggered! I just went & had another look. Guess what i found Jim?
So do i pull this lever up to cold start, then push it down when it fires?
I've got the car on ramps atm, it will probably be 2 weeks before it comes down. I cant wait to try this!

You pull it up to start and adjust the idle. As the car warms up you keep lowering the handle until it is at it's normal idle.

I normally let it idle at about 1500 to start. As the car warms up, the idle rate will increase and you keep pushing the handle down to keep it in range. Once the temp gauge atarts to move, I can usually close the hand throttle.

[coolngroovy]

No wonder it has been difficult to start! I'll try that, thanks.