CIS problems continue
 

So had a delay in my previous trouble shooting as i had flooded the engine, and a backfire cracked my pop off valve. Now that I got that replaced im back to working with my fuel issues and I cant get this dang car to run. It starts, revs and tries to idle but just dies almost immediately One thing that concerns me is that my pressures have changed. After disconnecting the hoses off of the WUR to make sure the screens are clean i only get 25 psi when cold. I cant get a warm side pressure since i cant get this thing running. (WUR resistance is about 26 ohms and i have voltage at the regulator). Right now im considering replacing the WUR. What do you guys think? Are any of you guys in the DFW area available to come out and take a look at this thing with me?

CIS troubleshooting.......
 

PM sent.

Tony

I see that Tony has sent you a PM--you are in good hands now. My only request is that you continue this thread with the information/results you get from following Tony's advice. It is important that others with similar problems learn of the causes and solutions. Please keep us updated on your progress.

About the PM.......
 

Larry,

The PM was all about him considering replacing the WUR. I strongly advised him not to replace CIS component/s like WUR unless it has been tested and confirmed defective. Otherwise it would be a costly way to fix things.

He called me and we had a nice long conversation until my wife reminded me for being late to my afternoon appointment. BTW, I always encouraged people to post all the actions done for the troubleshooting and share the experience with others. I will let the OP post the fuel pressures he had obtained and continue the discussions.

Tony

i would suggest that you have a vacuum leak somewhere.
get a can of carb cleaner or wd40 and spray it on suspect areas with it running. when it runs differently you have found the area it is leaking from.

Vac leak would not be unlikely given the backfire.
CCP is a sliding scale, you need to check the chart of pressure vs temperature.
Replacing the WUR with another 20+ year old WUR serves no purpose, it needs to be a new one or have yours rebuilt. If you really think the WUR is at fault swap it out with one from a fully functioning car to verify. Don't forget system pressure as CCP can be in spec but the car won't run correclty if the system pressure is off.

The few times I forget to hook up a big air hose ( e.g., Aux air regulator) I would have the exact same symptoms. Including big backfires with the aux air reg.

mine had the same symptoms when I left a nut loose on one of the inlet runners. (long story). Nipped it up and problem solved.
I'd definitely be checking all your hoses, pipes and anything else around the manifolds.

Just to follow up on this thread. I took Tony's advise and started looking into components individually. I did replace the WUR with a known working one. I made the decision based on the pressures I was getting off of the test gauge. New WUR and no change in pressure. I disconnected the gauge and also noticed that the pressure wouldnt leave the gauge completely. I think i made a bad choice with the harbor freight fuel gauge set. Now i did get the Car running but i still have an issue. To get it to start and run I have to have the mixture rich enough that it oscillates. Any leaner and I cannot get the car to start. I did find that the airflow sensor was a little off adjustment so I adjusted the plate flush with the bottom of the housing. I think my next move is to check the timing If i can do it with the osculations. WD40 at the intake runners is another i will look into. although I am confident that i have no leaks its worth the test.

Once running I decided to take it down the street to see how it drove. It was obviously rich and popping with throttle so i turned around only to have the car die. Let it cool down and it started and ran for another 500 ft. I ended up pushing it the remaining 1000 ft back to my garage. I thought my AAR was not closing all of the way and that could be another issue. Tested it last night and it closes 99% at 170 degrees. Has anyone had an issue with a car not running or starting unless its is set to a rich mixture?

I got $5 that says you are sucking false air. Five big ones.

I want you to go at those leaks like a spider monkey.

I use carb cleaner. Way more volitile than WD 40. I like risk.

You had a backfire that was strong enough to crack your pop off valve.
Have you leak tested the intake system with a constant 5 psi air pressure and soapy water to check for leaks in the airbox.
Your symptoms really describe a cracked airbox or other large vacuum leak, especially with known working CIS components.

Get some friends to help. These guys were pretty cheap.

http://forums.pelicanparts.com/uploa...1381089262.jpg

Well we had questioned the AAR valve operation and that it was hot to the touch and not fully closed. So we put a cork in it and tried to start the engine. That resulted in a big backfire that cracked the hinge on the pop off valve. It was the result of stupidity. Although the problem was present before that massive backfire. It seems when I bought the car the mixture was set rich to compensate for something. It wouldnt run unless it had a high mixture setting. How do you test the box with the air supply and soapy water?

Dfwflyr,

I was just in Dallas on business this week. PM if you'd like and maybe the next time I'm there I can come by. Not sure when I'll be back that way right now.

http://forums.pelicanparts.com/porsche-911-technical-forum/758788-cis-troubleshooting-dummies.html#post7525984
Has a decent description for using a vacuum to supply the air. I used my compressor hooked up to the vacuum brake line fitting.

I just found that. I think im going to do the shop vac method tonight. One thing I dont understand is that if i had a leak wouldn't i be running a leaner mixture? Perhaps if it was an intake runner only one cyl would run lean and i would have to set the CIS rich to compensate for it. Timing is my other concern that I want to check.

The cork should have gone into the hose and not the AAR.

911 CIS Primer - Vacuum Lines

Find the leak with the bubble test.

Air box pressure test in situ........
 

dfwflyr,

With the engine installed in the car, testing the CIS air box for leak/s or cracks is not easy. There are too many areas behind and under the air box that are difficult to inspect. While it could be done in situ the test result is not as reliable as when you do the 'immersion test'. If you want to be 100% certain about the test, removal of the air box which would take a lot of man-hour is one of your options.

You need to eliminate the 'air leak' and refrain from tinkering the mixture setting. BTW, what's wrong with a 25 psi cold control pressure? As you have learned, switching CIS parts is not the way to do unless you don't mind spending unnecessarily for parts. What's your fuel pressures with the new WUR? Keep us posted.

Tony

I found that my fuel gauge was not working right. the needle would stick at 40 psi. Not liking that I have to order another one. I did hook a shopvac to the intake yesterday and discovered that the airbox is cracked along the joining seam. I have the large airbox which I cannot find anywhere but Pelican for $451. I spent the evening looking at adhesives that will bond/melt polyolefins. I have three choices that should work. I think Im going to buy another cracked airbox and test which adheasive works the best and see if i can run an additional plastic weld across the seam. In the mean time I will begin removing the airbox tonight.