Quote:
Originally Posted by ossiblue
A few comments.
First, take Tony up on his WUR testing or, at least, PM him and get specific with your questions. He has done lots of hands-on work with CIS and knows what he is doing.
Second, the WUR is the control pressure regulator--it goes by both names, the most common on this board is WUR.
Third, you apparently know how to do the pressure tests correctly. Currently, you have a residual pressure of "0", correct? When you cleaned out the WUR, did you replace the 0-ring in the diaphragm cover? (Sorry, I did not go back and re-read the entire thread.) Did you inspect the two diaphragms for any bends?
Fourth, 11psi is very low, below 1 bar. Most specs on residual pressure are ~1 bar so from the outset you are low. However, a functioning wur should still hold that pressure.
Finally, you might try the following and report back: You say your fuel pump runs with the ignition on (even though it shouldn't). When you try to start the car and it fails to fire, immediately shut it down and go pull the plugs--what do you see and smell? Are they gas soaked or dry or something in between? Remember, every time you crank the engine, raw gas is shooting into all the intakes at once. If you are not burning off that gas, it is accumulating in the cylinders and seeping into the crankcase and into the exhaust. You put in new plugs, so you should be able to see signs of ignition, if it's present.
The fact that you can't get ignition using ether makes me suspect fuel delivery may not be the major factor here.
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1. I'm going to PM Tony and see what he suggests.
2. I was referring to the workshop manual testing procedure - earlier CIS cars had two control pressure regulators - the WUR and another on the throttle.
3. I did not replace the o-ring. No problems that I could see with the diaphragms.
4. I agree that the pressure is low. I found a chart that showed a very low cold pressure for the '77 911, and I thought I would try that pressure. No change.
5. What are the "signs of ignition" that I should be looking for?
Honestly, I agree that it seems like more of an ignition issue than a fuel issue, but I simply do not know what else to test with the ignition. Spark at all six plugs and I checked the gaps (again). Tested the distributor (and installed it 180 degrees out of timing at one point). Nice bright blue spark at coil. Is there something else I should look for?