Stihl FS80AV Giving Me Trouble.

[John394XP]

Howdy folks, long time fan here.

I just got the deal of a lifetime on two weed whippers, a small Echo and a large Stihl. The people sold them to me for 50 bucks because they were 'broken' and a while later, after I'd dealt with the varnish and sprayed some ether into the butterflies, I had two functioning machines.

Trouble is, the Stihl had a Crack in the gas tank, so I replaced it with an old Husqvarna tank I had laying around. Put a new fuel filter in, and changed old fuel lines and primer bulb while I was at it. When I went to prime the carb (an old TeiKei slide carb) the bulb would NOT depress. It fills, draws fuel fine, and even works when I remove the line from the carb, but as soon as I plug it in, it won't budge

Figured I'd reach out, seeing as I know very little about these old carbs, and the machine was priming and running perfectly fine prior.

Any thoughts?

 

[Sam R]

Are you sure you've got the lines hooked up right to the carb/tank? If it won't budge at all it sounds like it's either trying to draw or return to something that has no give from that direction such as an inlet needle in the carb. Also are your hose diameters good for the tank? If you squeeze too big of a line into a hole it'll be compressed and probably give that same problem.
If you have a Mityvac or some kind of vacuum/pressure tester, I'd test the primer, tank and carb to see if there's an issue in there somewhere. It could be just a bad check valve.