The enrichment valve operates in this mannor. When the engine is started the valve is cool and in retracted state. As the engine runs 6-8 volts are applied to the valve and as the element is supplied power it heats the capulary inside the valve. This along with the heat of the engine causes the needle to expand. This is a controlled method so that as the engine gets warmer the enrichment circuit is leaned out until the engine gets to operating temp and shuts the circuit off.When you shut the engine off the needle will not immediately retract without voltage applied to it. Since it is a controlled operation the needle will retract along with the engine cooldown. If you bench test an enrichment valve it will take 1-2 minutes for the needle to extend with applied 12v but when you remove the 12 volts it will take a good 5 minutes to retract. Now this is on the bench and not on a hot engine. A hot engine the valve will take much longer to retract since the heat of the engine keeps it from retracting. If yours is retracting that quick it is due to a faulty or substandard valve. Again I hate to keep repeating this but the truth is most people will buy the cheapest part on ebay or elsewhere. You get what you pay for. Most feel the enrichment setup is a flawed concept, but it was Honda who developed the enrichment valve in the 1970's. As I said before I had never had to replace the one on my or my sons buggy, both 2005. Now my 150 I now run the Keihn 32mm with manual choke but I use my stock carb when I test run the rebuilds I do. My Challenger still has the stock carb with enrichment valve 2008. Its not just buggy parts, 5 years ago my dodge with 380000 miles blew the waterpump seal. Since money was tight I went to AutoZone for the pump, paid 60.00 for a brand new pump with lifetime warranty. A year and a half later the pump went out on the highway. I had to have it towed since I could not keep water in it and you just don't overheat a diesel. Took the pump off and got a new one warrantied. Now 4 months ago I notice anti freeze dripping under truck. Water pump again. This time I went to cummins and forked out 165.00 for a new pump. I spent 60.00 for the AZ pump with 4 gallons antifreeze about 7.00 / gallon, second pump was free but the towing bill was 105.00 plus 4 more gallons of antifreeze 7+ dollars / gallon plus my time . I had over 200.00 in 2 pumps with towing. The cummins pump will outlast the motor with over 400000 on it. I run into the same with thermostats Napa 16.00. One year later thermostat acting up went to cummins and spent 36.00 for the thermostat but again it will outlast the motor. I'm not saying that everything at AutoZone is crap but they purchase according to price. Cummins is more concerned with reputation. The same holds true with buggy parts. Bottom line is your enrichment valve is the problem doing from what you describe. Stick with the best quality parts known and you will have less problems.
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