I've had a bit of a clown show with my 3800 the past couple days.
After I got the new crank seals in and reassembled everything together for a quick test, I got it started and immediately noticed the difference that the new seals made. Made a small adjustment to the carb/idle and it was idling beautifully, even after letting it sit for several minutes getting warmed up.
All was well, until I decided to try getting some cuts in with it. Almost immediately I was back into the land of pain and suffering with the carb settings being constantly off. It was like I was right back to where I was before putting in new crank seals.
It wasn't until I got frustrated and turned the saw off to seat the hi/lo jets in to start over that I realized what was going on. The lo jet that I set at 1 turn out? It took 2 and 1/4 to turn it back on. The hi was 1 3/4.
The carb screws were vibrating out on their own.
I had this happen to me with my Mac 10-10A after I ran its carb through my ultrasonic cleaner. You could stand there, rev the saw and watch the dumb things turn out.
No big deal, I just put a drop or two of blue threadlocker on each one, set it to 1 lo, 1 1/8 hi and let it sit overnight.
The following day, I got the saw started again and everything was wonderful. The hi jet needed to be turned out just a tiny more, but once I did that I cut a full tank worth of fuel with no issues at all. Runs great, cuts great. Nice firewood saw.
But, of course, after I fueled it up again was when the plastic starter pulley decided to crap out on me. I hadn't noticed it before, but the teeth or whatever that grab hold of the starter pawls were all worn down. Worn to the point that when you give a strong pull, the pawls just slip and chew up the teeth even further.
So that's where I'm at now. 3800 is back to being dead in the water until I can get my hands on one of those pulleys. How's that for bad luck?
Your 3800 have this pulley?
I just sold the bare pulley but have a whole recoil set up left extra.
Poulan 3400 pulley also used in the craftsman 358 saws I got.