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Registered
Join Date: Dec 2003
Location: Centreville, MARYLAND
Posts: 938
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WUR testing ?
An advantage of a twin engine aircraft (or a large shop) is that you can check one engine against the other if you have a question. With aircraft you might swap a recalcrent item form one side to the other for testing. In my case I took the WUR from by car being overhauled (79) and installed it on my working car (78) to solve a starting problem. What it was doing was running real rough for the first 60 seconds or so before setteling down to a nice rumble. I took the WUR apart to see what was going on but could not find anything wrong so I started the following test.
I took my vac pump and put vaccum to the line on the side (vac port). I added 7 1/2 lbs of vac ( did not want to add more). In 10 minutes it had bled off to .2 lbs. Is this normal or is the rubber membrain leaking?  
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Old Tee all 911s sold |
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08-17-2008, 11:25 AM
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Cynical Misanthrope
Join Date: Dec 2001
Location: Campbell, CA
Posts: 382
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If it IS your WUR membrane leaking (and not your vac pump) then that certainly is not enough leak to affect fueling. Intake manifold is flowing hundreds of CFM, that leak is a cubic inch over 10min.
I'd suggest you put a control pressure gauge to see what your cold control pressure is. My guess based on your description is your cold control pressure is enriching way too much, but as soon as the WUR heats up it goes into range.
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X-1, AFM744, Jon, '92 C2 Turbo JE 8:1 pistons, 964 cams, 38mm intakes ported/polished/twinplugged, ARP hardware, B&B headers/exhaust, 355whp. Full-blown GT35R 3.2 intake EFI pending... Where my misspent time and money is currently going. Last edited by AFM744; 08-19-2008 at 11:23 AM.. |
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08-19-2008, 11:21 AM
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Registered
Join Date: Dec 2003
Location: Centreville, MARYLAND
Posts: 938
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Thanks. This WUR has been replaced from the one on my 79 which fixed the problem on that car. So this WUR is misbehaving. I think you are correct, the test eliminated the membrane as the problem. I need to do some more tests on the heating portion and see if there is a problem there.
It has taken a lot of time to get my 78 running like new. In spite of the success I do not feel I have a handle on CIS systems.
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Old Tee all 911s sold |
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08-19-2008, 05:40 PM
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