Stihl BG-56 temp starting issue

[jwest]

New to the forums, thanks to all who make it such a great resource!

I had no real exposure to working on engines for most of my life, but now in retirement I've made up for it and learned a lot. I've been pretty focused on 2 cycle engines as well as 3 cylinder diesels. Im still noob but still learning all I can. I have one piece of equipment with a recurring problem that neither I nor my local dealer (two different ones) can figure out so I'm looking for suggestions to track down.

I purchased a brand new stihl bg-56 from a local ace hardware about 18 months ago and the problem has been present since day 1. On the first start of the day, I press the primer bulb the proscribed number of times and the bulb always fills right up with fuel and the unit always starts with just one or two pulls and the engine runs very well/strong just as I'd expect. First start of the day is always perfect.

If I turn it off and set it down for a bit (when changing from front yard to back yard, usually about 30+ minutes), if I press the primer bulb no fuel will come through to fill up the primer bulb and it wont even try to start. Press the primer bulb all you want, no fuel comes into it and it wont start.

But if I let it sit overnight, next morning you press that primer bulb and immediately fuel comes into it and the thing starts and runs fine. So I guess in summary, if the engine is cold pressing the primer always gets fuel into it. If it's warm, it wont. It seems like an engine temperature-specific fuel block

First dealer said I simply didn't have enough fuel in the tank. Ridiculous, I've tested that.
Second dealer said there was some type of factory defect in the tank vent and they replaced that. Still fails as above consistently.

I've tried spraying out the carb, checking tank lines.... nothing seems to make a difference. I am just about to the point of buying a new carb just to see if that fixes it. Advice?

Thanks in advance,

J

 

[jwest]

Did I post this in the wrong sub forum? Would appreciate any thoughts or advice on this one if any of the experts have an idea :\

 

[beaglebriar]

I'd start by looking for kinks in the bulb lines. Cold may allow fuel to flow but once warm the line may be more pliable and closing off. If that isn't it, change the bulb and lines. Could be something loose there creating an air leak. Typically you do not need the primer bulb for starting. Choke until the engine pops then choke off and it should be running. Primer bulb can help when you run out of fuel or if you need to push fresh fuel through the carb in a hot start situation. But again it's usually not necessary even though it may be part of the start procedure in the owners manual.