bad warm-up fuel regulator?

Volkovich · 08-25-2002, 06:18 PM

I just got a 1979 911SC and brought it into the local mechanic for some minor issues.

I was having difficulty starting it in the morning, at lunch time, and after work, i.e. any time it sat for more than a few hours. It would crank over, fire, and then die. After 2-8 times it would eventually start and idle.

The mechanic said that the warm-up fuel regulator needed to be replaced. Does this make sense? If it does what else does this regulator control besides starting properly?

MotoSook · 08-25-2002, 06:51 PM

For about $70 dollars you can get a CIS fuel pressure tester from JC Whitney that will tell you if your Warm Up Regulator is faulty. If it is, there are some fixes you can do yourself. Do a search on this BBS and you should find good postings. Unless you test the WUR w/ a fuel pressure tester, you can't rule out any of the other CIS components (aux air valve, aux air regulator, thermo valve, thermo switch, cold start injector, etc,...)

If the car runs fine when warm, it may be something other than the WUR. The WUR when cold should cause the motor to run rich. If you have a bad thermo valve, the WUR sees vacuum when cold and does not provide the enrichment that the motor needs. The thermo valve opens when the motor has warmed up. You can check it by pulling its exit vacuum hose when cold. If it is not closing when cold you'll feel vacuum, you'll need a new one or try to free it up if it is gummed up. Be careful when you pull the connector to note orientation, use bright nail polish to mark mating surfaces on one side.

The aux air reg. should be open when cold to provide extra air, as in a choke. You can check this by removing the hose on the right side of your motor and looking into it with a small mirror and maybe a flashlight.

Check for vacuum leaks and intake leaks. You never know. Spray carb cleaner on and around the soft parts in case they are cracked and leaking. With the motor idling, the RPMs should increase if you have a vacuum or intake leak.

The list goes on and on!

Get a Bentley Manual (available through Pelican) or a Factory Manual (can get one on E-bay on CD or ??). The Bentley Manual does a good job of explaining the what CIS components do.

Visit this site too.

http://members.rennlist.com/jimwms/index.html

The books that I have which any 911 owner should have in their library: Bruce Anderson's book, Bentley, Hayne's and of course Waynes 101 Project book.

Volkovich · 08-25-2002, 07:09 PM

Thanks for the information. The manual I had was very poorly written. I ordered the two that you recommended and hopefully I can use that information to keep my mechanic on track... well at least until I feel comfortable wrenching on it myself.

MotoSook · 08-25-2002, 07:24 PM

No problem letting your wrench do the work for you, but this is a good opportunity to learn about the CIS in your car. It is much simpler than you think and the help on the board will make the work go easier. A WUR not too pricey, but learnign how your car works is priceless.

Good luck and hope you get it fixed one way or another soon, the weather will soon be just about right for motoring ( cooler than July but dryer than October...fun drives in the country...with the sound of an air cool motor at 4000+ RPM in your ear when you look in your rearview and see the leaves spray up behind you as you speed down a wooded country road, you'll know you're in motoring heaven)

You've got an excellent example of a 911 in the 79SC. Learn the ins and outs of it and you will enjoy it so much more.

Souk H.