whats up with primer bulbs

[echomeister]

Why only small saws got primer bulbs.
What do they do?
Can ya reliably start a primer bulb saw without pumping the bulb?. i ask cause they seem to dry up and crack eventually.

Why????

 

[holeycow]

Pretty much an unnecessary part, imo. As you said; failure prone.

I have a few saws with them. I try to not pump them too aggressively (like squish them inside out and flat). Especially in cold weather. I have no idea why they are on some equipment.

My purge bulb equipped saws all start readily as long as there is a bit of fuel in the bulbs. They are "purge" bulbs, meant to eliminate air pockets in the fuel lines and provide a continuous column of fuel is all. All of my saws without them start just as readily if they haven't been sitting for months. If they've been sitting for months, it just takes a few extra pulls. Like about 3 or 4. I use the bulbs as little as possible. Just like the decompression valves..

 

[sean donato]

They are purge bulbs as mentioned. Pull fuel through the carb to remove the air to facilitate easier starting. Have equipment thats never had a purge bulb break and others that seem to break every few years. Some of it has to do with quality of the material, some of it has to do with the fuel you're running. They have been better in more recent years, there are also ethanol resistant replacement purge bulbs available. I see no reason not to use them. Not that big of an issue from the amount of hand held equipment I see across my bench every year.

 

[RedneckChainsawRepair]

592 has a purge bulbs and pretty good size saw. 93cc and down https://www.husqvarna.com/us/chainsaws/592xp/

I still dont use them unless been setting for a long time to draw fuel through.

 

[MacAttack]

I've often wondered this myself, I always just assumed the purge bulbs were geared toward the homeowner grade stuff that spent more time on the shelf.

 

[Old2stroke]

Depends on the length of the fuel line, After sitting for some time, the line will be empty and with no purge bulb, you just have to rely on the choke and pulling it over a LOT to get the fuel up to and into the carb. Often it's quicker and easier to remove the air filter and squirt fuel into the carb throat. On some of my big saws with high compression, I would love to have a purge bulb. Another advantage is ease of draining the fuel for storage, don't have to run them dry, just drain the tank, pump the bulb until it's just sucking air, then drain the tank again.