FWIW, when my car wouldn't start after doing these tests, I went through the system looking for significant vacuum leaks. I looked for vacuum leaks a year or so ago, and sprayed around various joints to see if it would change the rpm, and found nothing. This time, I actually noticed one of the intake rubber joints was wet! Then I found that the hose clamp was totally loose. I tightened it up (which was no easy task).

At the same time, Larry had mentioned to always double check the air sensor plate, and that the top of the sensor plate lines up with the edge where the funnel goes from a cone to straight down. He said that it should line up at the end furthest from the fuel distributor. I actually found that mine was lined up at the side closest to the fuel distributor. So, I readjusted it.

I finally got my car to start again. I now think that I just had too much air in the lines after the pressure test. But, more importantly, I have solved the early morning start issue. It snapped right up today. I don't know if it was the hose, probably, or the air sensor plate. But, it is a marked improvement.

Now I am going to try to add the vacuum line to the 009 WUR as Larry insists will be another big improvement.

Thanks for all the help here.

Jay

So I installed the freshly rebuilt 009 WUR in my 73.5 CIS. If I install it without using the vacuum, the car runs smoothly, as it did before. When I hook up the vacuum, and readjust the mixture, it will not run as smoothly - at any mixture position between obviously too lean and obviously too rich. It idles and drives fine. Just not as smoothly - a bit more gruff or uneven. Not drastically so, but obvious.

I have two suspicions: (1) with the 009 hooked up to vacuum, the normal pressure of the fuel stays much higher than without vacuum, and much higher than a stock 73.5. So I'm wondering if there are other parts of the 73.5 system that do not do well with the higher fuel pressure. (2) without the vacuum, the fuel pressure is completely static. With the vacuum, even when the vacuum is mostly constant, perhaps there are enough pulsing fluctuations in the vacuum that it similarly pulses or fluctuates the fuel pressure. Maybe the 73.5 CIS system is sensitive to those fluctuations, and the newer systems that used the 009 were revised to not be sensitive to the fluctuations. Someone suggested that there might be some sort of vacuum device that would go in the line to smooth out the vacuum pulses. But he is not a Porsche guy, and I don't know if there is such a thing.

Anyone have any thoughts on any of the above? Any other suggestions?

I am comfortable that when I hook up the hoses for the vacuum, they are on especially tight with no leaks.

Oh, and I'm pulling the vacuum from a T I've added to the hose that goes to the top of the decel valve.

CIS components.......
 

Jay,

You have done a lot of troubleshooting work but I never saw anything about your fuel pressure readings. Are you using a TTV (thermovalve)? If not, that's something you have to consider if you want your engine to run good like the other 911 CIS engines. WUR-009 needs a vacuum source. I was away traveling when you started this thread and had some what forgotten about it.

So what's problem/s are you having now with WUR-009? It is calibrated like it should be? BTW, you have to totally disconnect or remove the TPS if you are using the vacuum assisted WUR-009. Keep us posted.

Tony

Yes, the pressures before were all correct. All I did was take my 009 and send it to Larry for rebuilding. I put it back in, without retesting the pressures. It works just fine without the vacuum - just fine. So I feel that is a pretty good gauge that everything else is largely in order. It goes south when I hook up the vacuum.

I am not using a TTV. But as I read it, that has an impact only on start up. Otherwise it is dead weight. So that would not impact this. I am not using the TPS. But I'm thinking that if I don't get the vacuum to work, I might run the TPS with the static 009 when not hooked up to vacuum.

The problem is that it is running a bit rough when the vacuum is hooked up. No matter where I adjust the fuel mixture, it stays rough. I've turned the mixture richer and richer, a 1/8 turn at a time, until I get that drop at idle. And then a bit more. Still doesn't smooth it out.

Follow up question.........
 

Jay,

I found an old PM from you while I was away about the WUR-009 not holding vacuum due to some sort of air leak. Have you resolved this problem after the rebuilt done by FlowTech? Secondly, base from you feedback, I suspect your engine is getting unmetered air (?). Keep us posted.

Tony

Tony has experience with vacuum WUR's so maybe he can help with information. From my understanding, the original WUR and TPS lowered control pressure and had a slight rich mixture at idle and full throttle. Midrange was higher control pressure and slightly lean at cruising. If the vacuum WUR keeps the control pressure higher at idle and midrange, this might give the slight rough running you experience. I don't know if the air flow meter cone angles changed with the '75 for the different WUR's. The change in angle of the air flow meter would affect the mixture being delivered. The later '75 model also had a different fuel distributor, as well as injectors, which could affect things.

If you have a good TPS, I would install that and the 009 without the vacuum connection, set the pressures to '73 control pressure specifications, and see if that helps.