Hard starting help

[dmaddox]

Hello crew. New to Porsche, but a long time gearhead. Normally (I am most familiar with old Toyota's) when I have a hard starting rig, I start with spark, ensure proper valve adjustment/timing and then move onto fuel delivery (tank to carb and jet/idle settings).

However on my car (2.0, 1968 911L, rebuilt carbs in 2019 by a reputable builder with factory settings/jets, permatune) I am having a terrible time with consistent starts. Even on warmer days. It is like firing up the Cat D4 we had on the farm, a 30 minute procedure, with checklist.

Turn key, let fuel pump run ~10 seconds.
Five pumps, turn the key, a sputter and nothing, 5-6 seconds of turning over.
Turn key back to allow pump to run again. Five pumps, start over again.

Repeat this for 10-20 minutes until it catches long enough. The colder, the longer. It is a bit embarrassing. Further, in every video, discussion, etc.. I have never seen others struggle with starting like this. I have also never had a car (and most of my cars are 60's and 70's era vehicles) be this difficult to start.

I have tried to search for a checklist or a plan of attack on how to solve this, but not knowing specifics to this car, my plan is to attack it like I would a Toyota 2F, which I previously mentioned.

Check timing, check valve adjustment, check fuel delivery (what is recommended PSI at carbs?), spark, etc..

Oddly, when running and warm, it runs perfectly without a hitch.

Thank you in advance for tips, advice as I am ready to learn.

[edmayo]

Check the accelerator pump discharge amount.

[dmaddox]

Thank you Ed - I have the FSM's and a few docs on how to check that. Is there any circuit or device that enriches cold starts? Or is this system a basic one fuel delivery setting - which is set at temperature and that is what you get.

The only reason I'd argue against accelerator pump discharge is (which I will still look into), is the car after 5 pumps and a turn of the key will "blub blub blub" and die. So it is getting fuel. If the accelrator pump was the issue, 10-15 pumps would see it idle a bit longer before dying. The behavior of this when cold starting is EXACTLY like trying to start any vintage engine without a choke.

[edmayo]

Just remove the air cleaner and look down the throats and operate the throttle linkage, you should see a definite squirt from each discharge nozzle for a start. (engine off obviously) you can get more specific later by measuring the quantity. The accelerator discharge is the only cold start device, there is no enrichment circuit,,,how many times you pump the throttle has no effect on how long the engine runs after start up. The accel. pumps merely get the engine going. Also do NOT pump the throttle while cranking. BEFORE cranking perform the necessary pumps, then while holding the throttle about half way open crank the engine, once it starts hold the throttle open enough for a few seconds to let engine run smoothly then back off and just keep enough throttle to maintain idle. If all is set correctly after a minute or so the engine will idle on its own at a lower idle speed, which will increase as the engine warms up. Porsche has never used a choke on a carb'd 911 engine. Realize there is only about 3" from the pump nozzles to the backside of the intake valve, and there is a pump nozzle for every cylinder.

[dmaddox]

Many thanks for the help and clarification. I’ll give this a shot and report back!