Tough Starting After Installing New Overflow Valve

[Sasquatch]

My '97 was running okay, but not getting the mileage it used to and not delivering the same power, boost, etc. I was also aware of the much-publicized "ticking" that everyone seems to mention when describing fuel-related problems.

So, I replaced the overflow valve with the "$35.00 (plus shipping) special, and I noticed an immediate improvement. The ticking was gone, completely. I also replaced the fuel filter, cleaned the AFE air filter, and flushed the fuel heater screen that same afternoon.

Next morning, the truck didn't start easily. Had to pump the pedal and turn it over a couple of times, and it coughed and sputtered starting up. I also thought I smelled raw fuel, but didn't see any signs of a noticeable leak when I looked under the hood. Driving the truck during the remainder of the day, it started up whenever I got in it, and there was no repeat of the problem...

But, next morning after sitting all night, the same exact thing.

My concern is that maybe I didn't tighten the overflow valve enough and air is somehow getting into the system. The old valve was pretty loose when I changed it out, requiring very little effort to remove, so I didn't over-tighten it when I put the new one in.

Once I've driven the truck during the day, it starts every time no-problem. It seems to be only the first start of the morning when there's a problem, and even then it's not a huge effort to start. It just doesn't start as easily as it used to before I swapped out the overflow. It'll sputter, cough for a second, then fire up. It's kind of like when you change your fuel filter, and you haven't gotten a perfect, 100% prime; the truck starts, but reluctantly.

This morning, same story, and I thought i could smell fuel in the cab, but I can't see it when I look around under the hood with a flashlight and check the most likely trouble spots. It looks a little like there's a damp spot right under the overflow valve, itself, but it's not really "wet," and could just be my imagination. I tightened the nut very slightly more, because I'm afraid to deform those washers and tear them up.

The truck always started instantly before changing out the overflow, so I doubt that i've suddenly developed another unrelated problem. I'm wondering if I could've gotten a faulty valve, or if there's some trick to installing it that I don't know about. I just unscrewed the old one, put the new washers on either side of the valve, and screwed the new one back in...

Any thoughts or advice would be appreciated.