Primer bulb

[Dave630]

Why do so many new saws have primer bulbs?? My saw is old and doesn't have 1, but it still pops on 1st pull every time. I also noticed many pro saws don't have them either. Thanks!!


Sent from my iPhone using Tapatalk

 

[cedarshark]

Primer bulb gets gas to the carb, presumably faster and with less effort than pulling the saw over with the starter rope enough to get gas from the tank to the carb. If you drain the gas after every use and idle the saw dry.....you will appreciate the bulb. Bulbs do need replacement once in a while.

 

[Dave630]

I had to replace one on my yard sale line trimmer which is what got me thinking .... Just seems like an unnecessary part unless you are missing the choke


Sent from my iPhone using Tapatalk

 

[Chris-PA]

I had to replace one on my yard sale line trimmer which is what got me thinking .... Just seems like an unnecessary part unless you are missing the choke


Sent from my iPhone using Tapatalk

They do two different things. A primer bulb (more properly called a purge bulb) pulls fuel from the tank, through the carb and pumps it back to the tank to clear the air from the lines. A choke makes the mixture richer for cold starting - it will pull fuel through the lines too, but it takes longer - works best with short fuel lines.

 

[hamish]

Three different things.

A primer injects fresh fuel in to the carb.

An air purge and choke operate as mentioned above.

Terminology vs actual actions vary within the industry, and the marketing geniuses.

 

[mountainlake]

Why do so many new saws have primer bulbs?? My saw is old and doesn't have 1, but it still pops on 1st pull every time. I also noticed many pro saws don't have them either. Thanks!!


Sent from my iPhone using Tapatalk

What kind of saw do you have that starts on the first pull every time, I have over 30 saws most brands and only once in a while will any of them start on the first pull when cold and that only when it's hot outside. Most take 6 to 8 pulls if they've been sitting over a week and 2 or 3 if just sitting over night. The ones with primer bulbs will start in 2 or 3 pulls no matter how long they sit if I pump the primer up. Steve

 

[cedarshark]

What kind of saw do you have that starts on the first pull every time, I have over 30 saws most brands and only once in a while will any of them start on the first pull when cold and that only when it's hot outside. Most take 6 to 8 pulls if they've been sitting over a week and 2 or 3 if just sitting over night. The ones with primer bulbs will start in 2 or 3 pulls no matter how long they sit if I pump the primer up. Steve

He must have an electric one.

 

[stihl041avhog]

primer vrs purge valve. primer shoots gas into the intake. purge pumps gas to the carb into the tank as an bypass. no I never cross lines. The newer saws flood very easy nowdays

 

[Dave630]

Sorry let me clarify: it fires the 1st pull every time. I then set the choke to 1/2 and it starts on the 1st or 2nd subsequent pull. A primer bulb just seems like an extra unneeded part.


Sent from my iPhone using Tapatalk

 

[Dave630]

He must have an electric one.

I have a Jonsered 630. Perhaps you should try one


Sent from my iPhone using Tapatalk

 

[mountainlake]

A Josnered 625 I worked on started the same as any other saw. The only way a saw would start on the first pull when cold is if the low was way rich or if the needle was leaking a little gas Steve

 

[zogger]

A Josnered 625 I worked on started the same as any other saw. The only way a saw would start on the first pull when cold is if the low was way rich or if the needle was leaking a little gas Steve

I had one saw I traded off that would usually start first pull cold, a mac eager beaver. Perhaps how I had it tuned, never ran it much at all, but it started and cut OK.

 

[Dave630]

Like i said, it pops on the 1st pull then starts on the 2nd or 3rd when you take the choke off


Sent from my iPhone using Tapatalk

 

[Chris-PA]

This has mostly to do with how well the various check valves, inlet needle and tank vents seal, along with the tuning. If it all seals really well and no air backs into the lines while sitting it will start fast. It's just chance and cleanliness, mostly a function of the carb not the brand of saw. Even a good check valve may allow a little air past over time, which would not effect the way it runs.

A purge bulb eliminates that chance by removing the air from the lines. It also allows you to tell if the check valves in the carb are leaking as it will keep drawing air at the carb. If it does that, you probably have a ZAMA C1Q.

 

[CTYank]

Sorry let me clarify: it fires the 1st pull every time. I then set the choke to 1/2 and it starts on the 1st or 2nd subsequent pull. A primer bulb just seems like an extra unneeded part.
Sent from my iPhone using Tapatalk

Having a variety of 2-strokes with and without a PURGE bulb, I can say it's most definitely NOT unneeded. Makes the starting drill totally consistent, free of the drama of marathon cranking while you listen closely so you don't miss that first furtive pop, and then flood it.

Some saws will totally wear you out at times while you try to pump fuel up to the carb by cranking. Poulan 3400 comes to mind.

Once in a while I accidentally demonstrate its utility to myself, by forgetting to use it. After the sixth or seventh crank, I catch on.

If you put a saw away dry after using it, you really appreciate the ability to purge the diaphragm chamber of air next time you go to fire it up. I'd say it's a pretty safe bet that saw mfgs don't like to waste their time and bux with useless appendages.

 

[Dave630]

I have heard NOT to store them dry because the seals and diaphragms will dry out. I use non ethanol gas. What is your take???


Sent from my iPhone using Tapatalk

 

[jus2fat]

To me anyway..it depends on what it is. For instance..I always keep at least 2 chainsaws ready for action immediately if necessary.
( have a few cans of True-Fuel for these and this purpose )

On the other hand..I know I'm NOT going to be running a weed-eater in the winter..so these get run dry and stored..grease on seals.

Brush-cutter..I might use anytime..so "ready' - - hedge trimmer= summer only..so run dry and stored..with grease on seals.
( and the one's stored..I pull plug and put about a teaspoon of Marvel Mystery oil around piston..let sit overnight..then turn on up to TDC )

J2F

 

[old-cat]

My STIHL 4-mix weedeater fires first pull almost everytime. When I bought my new MS461, it started running first pull. Then two or three times after that, same thing. After I put some run time on it, it acts like any other saw, pull-pull-pull-pull pop then run.

 

[Dave630]

To me anyway..it depends on what it is. For instance..I always keep at least 2 chainsaws ready for action immediately if necessary.
( have a few cans of True-Fuel for these and this purpose )

On the other hand..I know I'm NOT going to be running a weed-eater in the winter..so these get run dry and stored..grease on seals.

Brush-cutter..I might use anytime..so "ready' - - hedge trimmer= summer only..so run dry and stored..with grease on seals.
( and the one's stored..I pull plug and put about a teaspoon of Marvel Mystery oil around piston..let sit overnight..then turn on up to TDC )

J2F

So you are the batman of woodcutting?? Just throw up the sign and you are ready at a moment's notice!!!


Sent from my iPhone using Tapatalk

 

[fearofpavement]

I rarely drain any equipment of fuel. If I'm using a saw, I leave it however it was when I shut if off. ie, I don't empty tanks for storage and I don't fill them either. I try to use everything regularly but sometimes it can be quite a few months...

Just last week I pulled the rope on a new to me saw and it fired on the first pull. Surprised the bezeebers out of me.