How Does The Carburetor Get Its Prime?
- Thread starter buddie
- Start date
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impulse line ...
is that technical enough ??
is that technical enough ??
Bob Wright
Addicted to ArboristSite
By the diaphram pump in the carb. Pulling the rope creates a vacuum causing the pump to wiggle. Hows that for plain english...Bob
Bob Wright
Addicted to ArboristSite
Look at #1 in the pic of the starting circut maybe this will help. From Mikes fine site...Bob
Chain Saw Carburetor
Chain Saw Carburetor
Hank Chinaski
Number 37
by my primer bulb that I push on.
Thank you everyone for your fine replies, you guys are great. I sure do understand the priming sequence now, however, my saw still doesn't fire up like it should. Runs great though if I squirt fuel in the carb at start up. I rebuilt the carb, got new tank breather vent, new air filter, rubber fuel and impulse lines are good for pressure but still no luck. I thought I could troubleshoot this myself but I think it's time to take saw to doctor, I have spent 3 weeks in my spare time fiddlin' with it. Thanks for your help.......
Cheater! (Where can I get one of those Number 37?)
Bob Wright
Addicted to ArboristSite
Make sure your gaskets and pump diaphrams 21-27 on the picture are in correctly. Ask me how i know (yes i put one upside down) and the saw would only run dumping gas down the carb. Flipped the diaphram over and it fired first pull...Bob
Hank Chinaski
Number 37
LOL dunno, I think my husky is the only one I've seen on a big saw, but mine doesn't have a choke
what saw do you have? There's plenty of smart folks here that can help if you'll let 'em.
BigMoneyGrip
ArboristSite Operative
I think it's from the pressure in the tank. Give the saw a couple of shakes and then pull the fuel line off. That baby will skeet fuel across the shop.
sunfish
Fish Head
Did someone say "choke"... :msp_wink:
Thanks for the continued advice. I have a Stihl 026. I'm sure the diaphragm and gasket are in properly. It was doing this stunt with the factory built carb and having rebuilt it with a full Walbro kit, still doing the same thing. I got that carb clean as a whistle too. Runs like a champ once it fires - I really love this saw, I've had it for 14 years but it's becoming a love-hate relationship. I guess the next thing is to replace the impulse and fuel lines. I've noticed the master control switch is a bit funky, it wants to hump up across the shaft when it is engaged to the trigger and maybe that is creating bad positioning of the throttle. That switch totally by-passes the half-start position and goes straight from cold start to full run when flipped. Only 15 dollars plus shipping for a replacement of that little piece of dubious plastic.
The spring with the kill wire keeps bending and hanging up on the throttle steps plus I have to try a few times to shut the saw down because of poor kill contact. If I keep this up, I will have a whole new saw - an expensive new saw as these replacement parts are spendy! Or I can invest in a box of hypodermic syringes to nurse this carb with fuel every time I want to start it. Thanks everyone, I really appreciate the support!
The spring with the kill wire keeps bending and hanging up on the throttle steps plus I have to try a few times to shut the saw down because of poor kill contact. If I keep this up, I will have a whole new saw - an expensive new saw as these replacement parts are spendy! Or I can invest in a box of hypodermic syringes to nurse this carb with fuel every time I want to start it. Thanks everyone, I really appreciate the support!
My 064 is really hard to get going as well. The impulse is new and the carb was rebuilt but no matter what it wtake way too many pulls to get it going. Now every time I am going to use it I just squirt a tad of fuel in through the carb using a small plastic water bottle that I burnt a tiny hole in the lid. Works great, saw starts after 3 pulls and 1 after warm. I never could figure it out.
I feel your pain. Gotta be a solution to this. My saw is loved and well cared for so it's not an abuse or maintenance problem.
BigMoneyGrip
ArboristSite Operative
Let your saw sit for a few days and then pull the fuel cap off. You should hear a hissing from the pressure escaping the tank. If not, replace the fuel cap. With your saw taking so many pulls to start when cold, leads me to think fuel tank pressure is bleeding off. The carb is having to prime the whole fuel line then. Once it does, it will start on the first pull.
albert
Addicted to ArboristSite
I would remove the air filter, which contains the choke. Choke it with your thumb for a pull or 2. If it starts normally, then your problem is with the airfilter/choke and or the control shaft. There were alot of bad airfilters on 026's that concerned the choke not closing tight enough.
The 026 has the choke built into the air filter. Make sure the throttle lever is pushing the choke all the way closed.
Check - Hissing sound present
Check - Brand new Stihl brand air filter installed last week, choke flap seals good...
Check - New fuel line, master control switch and switch spring installed today as well, choke flap fully closed, still no startie.
HOWEVER......
I got adventurous and sucked on the carb impulse inlet. Tongue stuck by pressure to inlet until release:msp_razz:. Blew into impulse inlet and heard slight gurgling.
Tried to start saw after that and it lit on second pull...... SAW STARTIE!
Could someone please explain this phenomenon? Maybe an impulse thing which I am utterly unfamiliar with. Impulse hose is fine, no cracks, holds good pressure. THANK YOU ALL FOR YOUR HELP!!!
