P0306 Cylinder 6 Misfire Detected -solved

[cr4west]

This post is just a reminder for folks with the 3.3L V6. Many of you are getting up past 200k miles and SEL codes start popping up relating to O2 sensor, cylinder misfire, missing on acceleration, very rich exhaust at idle.
In my case the P0306 Cylinder 6 Misfire Detected. Turned out to be the fuel pressure regulator. It's vacuum supply hose originates right above cylinder #6. When the fuel pressure regulator diaphragm failed, raw fuel traveled up the vacuum hose and flooded out the #6 cylinder. This was after a good compression test and new wires and spark plugs.
Then we started to check fuel pressure by jumping the fuel pump relay. When we removed the rubber vacuum hose to the fuel pressure regulator we were surprised with raw fuel shooting out of the hose!

[guillotr]

cr4west ... thank you thank you thank you! Stumbled across your post yesterday and verified it on my Pathfinder last night. I've spent way too much time, money, and mental energy troubleshooting this same issue. The dealership had pointed me away from the regulator (and towards the injectors) ... but after troubleshooting/replacing plugs, plug wires, distributor, one injector, the rest of the injectors, two upper intake plenum removals, pcv valve, distributor wiring (that I had previously repaired) ... I can't believe it will be this easy!! When I pulled the upper intake plenum the first time and saw that the no. 6 cylinder intake port was clean (compared to the others), that really should have stopped me in my tracks. I would have been soooo mad if I had sold the vehicle to a friend and found out later that all it was a $100 fix. This vehicle has been in the family for almost 20 years. Hopefully it sticks around for a little longer! Thanks again!