Michael Mullen

My '77 911S starts hard when cold, but starts perfectly when warm. I've read that it could be the cold start valve. Can anyone tell me where the cold start valve is located? Is it part of the warm up regulator, is separate?

Thanks.

gustaf

The cold start valve is a PITA to get to. It is on the back side of the airbox. While it is possible to get to, there are things that need to be removed (like the blower motor) to make access possible. Even with that removed it is still a PITA to get out.
Hope this helps!
-Dave

Chris Martin

I am in a similar boat. There are some good tests to run in the Bentley manual to test the cold start valve. The starter should send power to the valve via a temp sensor. You can test for power at the temp sensor and the starter. I was trying to check out the cold start valve last weekend and cant see it, less get my hand on it.

Good luck

Hladun1

The first (and very easy thing) to check is the thermotime switch. It's on the left cam chain cover. Reverse the leads and see if that helps with cold starting. If it's connected wrong the cold start valve doesn't work.

David0514

What exactly is your car doing? This has been an on going issue with my car since I bought it. Mine just doesn't like to start with no gas on it's own. It takes about 3 or four try until it gets going but barely (low rpm's) and backfires a bit. Then eventually the rpm's shoot to 2000 or so and then fall to 800. Once it has been going for a minute it is fine. Also, starts great warm.
Let me know. The cold start valve is one thing I haven't checked.
Thanks.

Michael Mullen

David asked about exactly what my car does:

Well, basically, I have to crank the car for about 40 seconds before it catches. It catches reluctantly, spits and coughs a bit, then the revs go up to about 1,500 rpms. At that point, I usually pump the gas a bit to get it to stabilize. It then stabilizes at about 1,000 rpms. Otherwise, it starts perfectly when hot. I'll check the wires going to the thermostat when I have a chance (the car is with my Dad now). Hopefully I put the wires on backwards when I did the carrera tensioner update a few years back. If not, it looks like the cold start valve is in a bitch of a location to get to and will take some patience to take off and replace.

Thanks for the help to everyone who responded.

- Mike