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About TLK914

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    997, cayenne s
  1. And with regards to the original post, which I hope is already fixed (just posting all this because Im new and have been doing evap for 15 years all makes but porsche lately) since this had a pump sense circuit in addition to large leak...Id generally start with pump diagnostics (does it turn on/pump when commanded?) and is it getting vacuum (the small line). If its getting vacuum (remove the small line at the pump when running) and it cant see it...pump is bad. If there is a problem with the pumps diaphragm leaking internally so it never moves despite vacuum...same issue, bad pump. If its pum
  2. With all leak detection pump operated systems, the engine vacuum (or pump vacuum in this case) is sent back to the leak detection pump, it uses this vacuum and lifts and then releases a diaphragm in the LDP and that is used to "pump" air pressure into the fuel tank. (Yes, they use vacuum(negative pressure) to push and pull a tiny pump and it creates positive pressure...sounds weird but thats how it works!). When enough pressure is built in a calculated amount of time, the system seals and watches the pressure for decay. If no decay, its a PASS and in 2 consecutive passes, (on 2 consecutrive co
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