Luke Warm Starting Problem
 

I have a 76 911s with CIS that is having some starting problems. The car starts great when its cold and great when its really warm. The only time I have a hard time starting is when the car has been driven for just a few minutes and then shut off. The car then cranks for a long time before starting, the cranking will start at normal pace and gets faster and faster over a minute or so before the car actually starts with a big rev. It seems to me that the car is flooded at this point. My question is what are the common reasons that the car would be flooded? How can I test for these things? This is what I have so far

1. Leaking injectors - Should I just pull the injector and turn the key on and see if it squirts?

2. Stuck diaphram in the distributor (not sure what this is but I heard of it in another post)?

3. WUR issues?

Thanks for your help,
Jesse

On CIS cars a very common cause is the Fuel Accumulator.

Here a diagram from Pelican: http://www.pelicanparts.com/catalog/images/fuel_injection/new_images/fi_fuelsystem_2-1-1b6.jpg

I have replaced the fuel accumulator and filter.

OK, then besides what you've mentioned, the check valve on the fuel pump can be stuck. If you do a search you'll find info on how to check and fix.

.... http://forums.pelicanparts.com/showthread.php?s=&threadid=134458&highlight=check+ valve

I edited in the link to a related thread.....didn't want you to miss it.

Sorry, I should have mentioned that I did replace the check valve as well. I think I will start with the injectors and test for dripping after the car shuts off. The thing that I don't get is that the car starts great when its hot.

I'm sure others will chime in.

Let us know how it works out....

Mine was the fuel accumulator....

Good luck, David

when was your last tuneup?

I did a full tune-up about 6 months ago. The car has had this problem since the rebuild was completed.

Have you checked your gas tank for rust. Rust in the fuel system can cause many problems. And disable brand new replaced parts. Ask me how I know! Have you also checked the fuel pressure from the fuel pump and WUR. Pressures are very important.

I guess I am trying to narrow down the potential causes. The car runs great once started. Starts great cold, starts great hot. The only time I have a problem is if the car has only been running for a few mins and I shut it off. Therefore the pump obviously works well and there is not rust in the gas tank since that would affect the performance all around. My question is what factors would be present when the car was started and then shut off after a few mins that are not present on a cold or hot start?

One thing you may consider. When you turn the key or start the car the the filiment in the WUR heats up therefore changing the control pressure.

Rust im my gas tank never effected the overall performace but did create many annoying bugs such as this.

I now have an update. There where two problems. The first was that the timing was off because the smog station thought it was supposed to be 15ATDC and it was actually supposed to be 5ATDC. Once I fixed that the idle went way up when it was hot, so I adjusted the idle back down. Now the car won't idle when cold. So I think my cold start valve is the problem. There is a connector on the cold start value but I don't have any wires connected to it. My guess is that this connector supplies current which heats the valve causing it to close after the engine is warm. Mine isn't closing and so my idle goes too high when the car warms up. My question is does anyone know if there should be wires going to the cold start valve? If so is it just a switched hot that supplies 12V when the key is on?

Thanks,
Jesse
76' 911S

BTW When I say cold start valve, I mean to say auxillary air valve.