[urq] suddenly Lean - Now I'm Rich!
a.sigal at bluewin.ch
Tue Feb 27 13:56:44 EST 2007
Nice one Keith.
Get well soon , and then you could perhaps write the procedure and place
it our KB. In time, many will benefit for sure. Then if you so inclined,
and since you have the old unit for the test, can make your WUR
adjustable as per: http://www.rpm.com.au/911/html/tech_w.html
Thanks and regards,
>So I dismantled a KV WUR after first ensuring that the diaphragm was intact and it held vacuum/pressure. I reversed the orientation of the connector, re-assembled and ensured that it still held vacuum/pressure. Checked continuity - all OK.
>The WUR that I removed from the car did not hold vacuum or pressure so I think I may have found my culprit
>As I understand it the WUR works as follows:
>At cold, the valve within it allows free flow of fuel in the control pressure circuit, as the bimetal spring warms, it and the coils springs close the valve, increasing control pressure and leaning the mixture. So as the engine warms up so the mixture leans off to a normal running condition. Under this normal running condition the pipe from the manifold, routed by the inactive solenoid applies vacuum to the diaphragm in the WUR maintaining the spring pressure against the valve and thus maintaining high control pressure.
>Under WOT condition when extra fuel is needed in a rush, the WOT switch triggers the solenoid which purges the vacuum, replacing it with either ambient pressure or positive pressure causing the diaphragm to move away from the spring, allowing the spring pressure on the valve to decrease, opening the valve and reducing the control pressure, thus increasing fuel delivery. - Am I right in my understanding of it's operation?
>Anyway I then swapped WUR on the car for my checked KV WUR. I re-set basic mixture and took it for a test run. Then and since I have not had a "lean" incident.
>As Inspector Clouseau would say: "Kato my little yellow friend, I think the case is solv-ed"
>'63 Daimler V8
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