1977 911 targa 2.7l starting issue

[stevepell]

My 1977 911 Targa with a 2.7L CIS system does not want to start when the engine is cold. I turn the key and it cranks but hardly coughs or spits. The moment I spray some starting fluid into the intake box it fires right over. Once it runs a minute or two it will fire up without any issues? Cold start valve perhaps? Other ideas to look into?

Thank you.

Steven Pellnitz

[Showdown]

Start here:

https://forums.pelicanparts.com/porsche-911-technical-forum/758788-cis-troubleshooting-dummies.html

[HarryD]

Sounds like a cold start injector issue.

Look behind the throttle body and verify the cold start injector is plugged in.

Your have a thermotime switch on the face of the left hand timing chain cover. Verify it is plugged in. With the motor completely cold, pull the plug on the switch and check for continuity with an ohmmeter. Test the plug for 12v while cranking the car.

If these are ok, Try pressing your throttle all the way to the floor. This should activate your microswitch and energize the cold start injector.

[kach22i]

Originally Posted by HarryD

Sounds like a cold start injector issue.

Look behind the throttle body and verify the cold start injector is plugged in.

Your have a thermotime switch on the face of the left hand timing chain cover. Verify it is plugged in. With the motor completely cold, pull the plug on the switch and check for continuity with an ohmmeter. Test the plug for 12v while cranking the car.

If these are ok, Try pressing your throttle all the way to the floor. This should activate your microswitch and energize the cold start injector.

Interesting post HarryD, could you possibly post some photos of what is described?

On my 1977 I've found starting issues related to seasonal temperatures, and the Fuel/Air ratio mixture with minor adjustments makes quite the difference.

Of course I'm probably just circumventing other issues.

I made an adjustment about a year ago that must have been "just right" because this driving season has been fairly uneventful (in a good way). Sort of turned a long term cold starting issue into a hot starting issue, just not a chronic or severe one.

Stevepell, there are many other thread on this, I'm always amazed at the variety of solutions and what finally worked. There does NOT seem to be a "typical" solution unfortunately. I've learned to lived with not so perfect, others must have perfection. Only you can decide what is right for you.

[rwest]

Could also be that you are bleeding down all of the residual pressure in the system due to a bad check valve in the fuel pump.

Been awhile since I messed with CIS, so you might want to verify my following suggesting before trying. With the air filter out and the key in the run position, push up on the metal arm that is hanging down from the fuel distributor in the air box. You should hear the pump run- don’t do it for too long, but then try and start the motor. If it starts, that should be a good indication that your system is losing pressure when it sits.

[stevepell]

Thanks for the tips I will check them all out.

[pkabush]

Originally Posted by rwest

Could also be that you are bleeding down all of the residual pressure in the system due to a bad check valve in the fuel pump.

Been awhile since I messed with CIS, so you might want to verify my following suggesting before trying. With the air filter out and the key in the run position, push up on the metal arm that is hanging down from the fuel distributor in the air box. You should hear the pump run- don’t do it for too long, but then try and start the motor. If it starts, that should be a good indication that your system is losing pressure when it sits.

Wouldn’t a bad fuel accumulator produce these systems as well ?

[Paulporsche]

Steven,

There are many many threads on this. A search will yield lots of info.

In general, however, you should:

1. Make sure all your ignition components are functioning correctly and are in spec. EG a simple thing like points that aren't opening correctly can cause poor starting.

2. Make sure you have no vacuum leaks. EG The CIS works on vacuum to raise the sensor plate when starting since fuel isn't injected until that plate is raised.

3. Get a CIS fuel gauge. You have to check your fuel and control pressures. If they are incorrect, say from an out of spec WUR (warmup regulator), you will have start/run problems. This is very common in these cars.