Evap purge valve cycling every 10 seconds

[Spinbox57]

Hi all. New to Forum. I have a 2003 Expedition 5.4l . After replacing the evap purge valve, vent valve and gas cap I finally eliminated all error codes related to small and large leaks. However, I'm noticing that the evap purge valve on the firewall activates every 10 seconds or so, then turns off after 8 seconds of operation. It is noticeable as a air flow sound and a slight elevation of idle as well as a change in fuel trim that indicates the CPU is richening the mixture. Verified that this is the source by clamping off the vacuum hose from the engine to the purge valve. Does this sound like there is still a leak at the gas tank or canister? I have no error codes these days. Thanks in advance! Jeff

 

[Jb14]

Welcome @Spinbox57 that does sound odd I just recently had an Evap error and for me luckily it was just the fuel cap. Couple of things you can try, if you have the old valve try switching it with the new part to see if you are having the same effect if not then maybe the new valve is possibly defective. Have you checked the vacuum lines for leaks and checked to see if the canister is not cracked?