Primer Bulb Operation

[Old2stroke]

I hope you don't mind me reposting your info from forestry forum. I thought it was good information that the op might find helpful.

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Not at all, accurate info is always good wherever it comes from. There might not be as much confusion with this little device if the industry had started with it's correct label of "purge valve" rather than "primer". Anyone reading their manual and seeing "primer", thinks it is supposed to squirt fuel into the engine/carb.

 

[ammoaddict]

Not at all, accurate info is always good wherever it comes from. There might not be as much confusion with this little device if the industry had started with it's correct label of "purge valve" rather than "primer". Anyone reading their manual and seeing "primer", thinks it is supposed to squirt fuel into the engine/carb.

I agree. I did read a manual that called it an air purge. But like you say, most call it a primer. That can be confusing little devices.

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[oldfortyfive]

Great info....FYI, it works differently on the Stihl 500i. As I understand it does actually pressurize the fuel injector system.

 

[redunshee]

I'm hoping you meant to say "fuel tank" and not "cylinder" ?

yup. meant fuel tank

 

[redunshee]

Great info....FYI, it works differently on the Stihl 500i. As I understand it does actually pressurize the fuel injector system.

Makes sense being fuel injected

 

[Canyon Angler]

The primer bulb on my Dolmar top-handle saw cracked a few years back and I didn't have time to mess with it, so I just left it there but didn't use it. Instead I just choked the cr@p out of it and started it up. Ran fine without the bulb. I ran the saw for a year or two like this before finally replacing the "primer bulb."

Next time the bulb cracks, I may just investigate how to take it out of the loop, since the saw seems to start and run fine without it, cracked or not.

 

[Old2stroke]

The primer bulb on my Dolmar top-handle saw cracked a few years back and I didn't have time to mess with it, so I just left it there but didn't use it. Instead I just choked the cr@p out of it and started it up. Ran fine without the bulb. I ran the saw for a year or two like this before finally replacing the "primer bulb."

Next time the bulb cracks, I may just investigate how to take it out of the loop, since the saw seems to start and run fine without it, cracked or not.

As you have noticed, the bulb has no effect on how the saw runs, it's just there to get fuel into the carb without a lot of pulling. Even with the bulb cracked, there is a check valve that stops air from being sucked back into the carb. The easiest way to disable it is to pull the bulb line off the carb and plug it by pushing a small ball bearing (or piece of nail) up the line and then push the line back onto the carb. Easy to put it back in service if wanted.

 

[grizz55chev]

As you have noticed, the bulb has no effect on how the saw runs, it's just there to get fuel into the carb without a lot of pulling. Even with the bulb cracked, there is a check valve that stops air from being sucked back into the carb. The easiest way to disable it is to pull the bulb line off the carb and plug it by pushing a small ball bearing (or piece of nail) up the line and then push the line back onto the carb. Easy to put it back in service if wanted.

Or spend a couple of bucks and 15 min of your time to make it an easy starter?

 

[Okie]

lots of info on-line about your question and how to test a primer bulb and how to determine correct fuel line routing for such.

I had to also review such first time I ran into a stand alone primer bulb hooked up wrong.