Yes, another cold start problem
 

I have a 1973 T motor that has been upgraded to a 2.7, with CIS. The problem is when the motor is cold it takes at least 6 and sometimes up to 10 long cranks to get it to start. It doesn't matter what I do; foot off of pedal, half way down etc.) When the motor is warm it starts immediately. I've had the cold start valve replaced with a larger valve, but this has made no difference.
The motor has a fairly wild cam in it (don't know what) and runs poorly under 2200 rpm. Would this wild cam have any impact on cold starting? Any help would be appreciated.
Ron

I've done some searching and come up with the following things to check:
1. warm up regulator
2. thermo time switch
3. check to make sure that plugs are gapped to.030 instead of the recommended .060 by Perma Tune
4. New plug wires-the wires in the car are 18 years old

Any comments on the above list. This is my first Porsche and I know very little about CIS.
As I mentioned in my above post, the motor starts when warm, and if it is warm enough outside (in the 70's) the motor will start immediately even after sitting for 8 hours. But, if the temperature drops down into the 50-60 degree range and the motor is cold, it is very, very difficult to start.
Also, I had a new fuel pump installed and fuel regulator.
Ron:confused:

Elaborate on what exactly you have in your car in terms of an engine and fuel/induction system.

Is it a 2.4 liter 73T MFI or CIS system that was changed to a 2.7 liter during a rebuild and a new CIS fuel/induction system added to it?

Or was a complete 2.7 engine and fuel/induction system from a later year installed in the car?

Does the airbox have a pressure relief valve (pop-off valve) installed (look under the air filter); if not look for a cracked airbox.

The fuel distributor has to be matched to the engine displacement.

CIS fuel injection doesn't operate well with "wild" cams.

I'm not sure what you mean by a fuel regulator; there is an accumulator installed near the fuel filter and the fuel distributor is mounted on the airbox; there is a big difference in cost ($60 versus $600 to $1000) so I suspect it was the accumulator that was replaced.

The orginal 73 T CIS system (sometimes known as 73.5 T) didn't have a thermo-time switch in the cold start valve circuit and in fact the cold start valve was only energized (while the starter was turning and only while the starter was turning) when the left lever next to the handbrake was fully pulled up (provided everything was connected and working). You appear to have a "hybrid" system so I would first confirm that the cold start valve is getting power during starter cranking and that it's actually working.

Plugs, wires, points, distributor rotor and cap and engine timing in poor condtion and/or out of of adjustment will also make starting hard. 18 years is old enough - replace the sparkplug wires. Check timing and dwell and adjust as required.

One needs a CIS pressure test rig to trouble shoot the WUR's condition/operation.

Cheers, Jim

I understand completly your frustation IM 84 Flier because my 911 has excatly the same set-up. It is a 73 targa but with 74 2.7 L CIS k-jetronic fuel injection sytem. I had compare the 73 and the 74 and the person is right about the cold start circuit beeing energized during cranking of the motor. It shows clearly into the wiring diaghram. When i check my cold start valve, there was no fuel supply to it and wasn't even energized in anyway shape or form. So it is taking me for ever to start the car. BUT, once it is warm, it runs like a clock.
So, yes, the set up is completly different for the cold start valve for 73 and 74. The 73 is a 2.2 L MFI (mechanical) and the 74 model is Bosch CIS k-jetronic fuel injection system. We have to make sure of 2 things for the cold start valve:
1.That the cold start valve is getting fuel.
2.that the cold start valve is getting electricaly energized ONLY during cranking of motor according to the wiring diagram and to the specifications of manufacturers so to speak !!!
I have found the problems and am now confident enough to fix the problems.
Keep in touch, truly Philippe.

What would be the thing to check if the cold start valve is getting energized but isn't getting fuel?

B

Well, i would make sure the cold start valve is getting fuel. For that, you have to deassemble the cold start valve from airbox. If you have book, it shows clearly where the cold start valve is connected : left side behind the airbox, i have done it and it is kind of a pain so take your time and be very meticulous. Be careful not to loose any rubber seal or screws.
What i do it's i use a mirror that i put behind the airbox and work from there. It helps a lot !!!!!
Once the cold start valve dissamble from air box, find a container and see if that valve is spraying fuel when it is needed (when engine is beeing cranked for cold starting).
If you don't get fuel, it's either the fuel supply or the valve itself that is faulty. Just work upstream (before) from the place of the problem !!
Good luck !!! Philippe.

Be sure the hand throttle is lifted up when starting the car and also be sure the hand throttle lever is actually connected to the throttle cable. If I forget to lift up the throttle lever on my '74 with CIS, it will take many cranks to finally start. With the lever lifted, the car start on the second crank!