OK sportsfans, I flew up to Talkeetna a couple of Saturdays ago - just because. Beautiful morning, hoping to get there and back before forecast winds kicked up. I landed, used the facilities, and talked to the briefer. AWOS back at Birchwood was calling for calm winds. hopped back into the plane, took off, and at about 400 agl got a "hiccup" in the normally smooth running PPonk engine. I pulled carb heat on immediately, dropped the nose a bit to build some airspeed. The engine smooted right out so I and continued on. I flew the rest of the way home with partial carb heat, monitoring the carb heat temp (stayed in the 80's all the way home), and the engine ran just fine.
Upon arriving at PABV, the winds were blowing 20 and gusting to 35, 20-40 degrees off the runway, so I had to work to get her down on the long and wide runway. Once down, I taxi clear of the runway and head to my tiedown. Right in the middle of the taxiway the engine quits. No hiccup, no burble, just dies. I check my fuel selector (Both), and tried a restart. It turns over fine, but doesn't start. I go to prime a couple of times, and there's literally no pressure on the primer, leaving me to believe I'm out of fuel
However, I took off with 45 gallons from Birchwood, and used less than 20 on the round trip (I do have a totalizer). A couple of guys passing by on the ramp helped me to push her back to the tie down, and I got it secured in the relatively high winds (I came back the next day to put the wing covers on - not possible in the wind that day). I dipped both tanks, and found that my R tank had the 25 gallons I thought to have in my tanks, but the L tank was bone dry. This is the point at which I REALLY wanted a drink! If this had happened just five minutes earlier during that nasty approach in that wind . . .
So I get with my mechanic and he checked out the plane. Parked it in a hangar and checked the vent system. It checked OK, but the vent was badly out of position, which accounts for the uneven fuel flow. There's no way of knowing if the vent line was blocked and an obstruction was blown out - but it's venting properly now . . .
The fuel valve checked out OK, so it was time for a functional check. I taxied out and did a run up on both tanks, and then ran on each tank separately for about 5 minutes at run-up rpms (1700). Everything checked out fine, so I taxied onto the runway and took off.
I climbed up to 5,000 ft. and flew in a circle for an hour, staying within easy glide distance of the airport, I flew on Both, L, and R about equal time to check out operation.
Everything worked as advertised. I flew five TnG's, and landed to refuel. The fuel flow meter showed 18.3 gallons used in the 1.2 hrs., and I refueled exactly 18.3 gallons, filling to the filler necks, 9.3 in the R and 9.0 in the L.
At this point my mechanic and I have decided that it was one of those "gremlins" . . . most likely associated with a vent problem, but I'll never know for sure.
I also learned a lot about the fuel system in my airplane. While familiar with it, I think I know it now, and understand how important the positioning of that little fuel vent is. The Cessna service manual gives a .09" tolerance for placement - that's right - nine 1/100th's of an inch.