# Request for help with Poulan weedeater



## Ron_in_Conn (Jul 2, 2008)

Hello. Wonder if I can beg some assistance with a Poulan BC3100 2-cycle weed whacker. As with many, my fuel lines were rotted, so had to replace. I'm pretty sure that I re-assembled properly: small diam. hose with fuel pickup on the end from fuel tank to lower port on carb, larger diam. hose from upper port on carb to suction side of primer bulb, larger diam. hose from output side of primer back to fuel tank, with a little plastic piece on the end to keep it in the tank.

Here's the rub: when I press the primer bulb, it jets air / gas up into tank, but doesn't reinflate quickly; takes some fiddling with before gas comes back in to it. Additionally, no gas seems to be getting through carb, since I see little air bubble in the small hose going from tank to carb, and, of course, the think won't start. Runs briefly on starter fluid, but sure doesn't seem to be drawing any gas.

The last little worry I have is that there's a little duckbill valve that I couldn't find a home for after replacing the fuel lines. 

My questions are: where does the duckbill valve go? Could absence of valve cause the primer not to reinflate and no gas to be going to carb? Or, is it just a matter of that the thing sat for 2 yrs. until I got around to replacing fuel lines, and I have your basic clogged carb?

Sorry - feel like I put my life story here, but would sure appreciate any advice. Getting divorced soon, and will need that spare weedeater.

Thanks in advance!


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## dawgpile (Apr 28, 2008)

Ron, you're on the right track so far. Two things could cause what you're seeing. First, the primer bulb could be shot and not very pliable due to age and need replacing. Second, the fuel inlet filter in the tank could be clogged. (or both of these!). Do a quick test by removing the filter in the tank and with the end of the fuel line submerged in fuel, try the primer bulb. If it properly re-inflates, the filter is clogged. You can test this separately by trying to blow/suck through the filter. Air should flow easily through it if it's not clogged. Don't rely on a mere visual inspection.

See how you make out with those tests and let us know. If you still have problems, post them and we'll go from there.

I am perplexed by your comment about a 'duckbill valve'. Do you have a pic?
I'm attaching the IPL for your ref and perhaps you could find it on there. Are your referring in any way to the metal choke lever? I'm not trying to insult your intelligence, but I'm not sure what you're referring to!

You should be able to source parts locally from a service place. They'll also handle the carb parts like a diaphragm/gasket kit if you need it(your unit has a Walbro 'WT' series carb on it).

Here's the IPL...


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## dawgpile (Apr 28, 2008)

Ron, I'm not sure how far you disassembled the unit. Is it possible you took it down to the reed valves and removed them? I suppose they could look like a duckbill! Look at # 27 and 28 in the IPL. If you removed them and didn't replace, then it will definitely NOT work!

Again, I'm just not sure of what you were referring to...

Let us know and good luck!


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## 30yearTech (Sep 14, 2006)

The duck bill valve most likely came out of the fuel cap, it is there to vent the tank. They are not generally shown in the IPL's as it's much easier to just replace the fuel cap. This should not prevent your unit from running, but it may allow fuel to spew out of the vent hole in the cap.

If you did want to try and replace just the duck bill valve I think the Poulan part number for it is 26119.


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## Ron_in_Conn (Jul 2, 2008)

Thanks, guys; really appreciate the expert replies.

The primer bulb itself still seems pretty flexible; I can twiddle it and sorta get it to re-inflate. If I remove the connection from the upper side of the carb to the small connection on the primer, it pops right back, with air.

I removed the in-tank filter and made sure hose was below level of fuel in tank, then went through the starting process. Pretty much same result; it'll run for 3 seconds on starting fluid or gas in the air side, but primer won't re-inflate unless I play with it, and it won't actually draw fuel through the carb.

Some clues (?): If I pressurize the tank by giving it mouth-to-mouth, the primer will generally reinflate more easily (and I get a great burning sensation in my mouth). Also, when I start it on fluid, a little gas is getting forced out of the fuel cap vent, which seems really weird, especially with the little duckbill on there (see below).

At this point, does it just sound like carb is fouled? If so, are there any steps I can take to try get some fresh gas / carb cleaner flowing without taking it apart? If I do clean it out, what part is most likely, in your expert opinions, to be the likely culprit?

Side note on the little green duckbill valve: It looks like it WAS intended to go inside the fuel cap, 30yeartech. It had a little spiky ring about the base which looks like it was meant to wedge into the cap. It had fallen into the tank, which was the cause of my confusion as to location. 

Thanks a ton again guys! I love these forums and really appreciate the expertise that's provided. If you're passing through CT, would love to buy ya a beer or two.


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## 30yearTech (Sep 14, 2006)

I don't think you will be able to clear this up, without disassembling your carburetor. It could have a plugged filter screen in the fuel pump side, a sticking inlet metering needle on the metering side, could also have stiff diaphragms.

A beer sure sounds good... but I don't have any plans to be out in your neck of the woods...


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## Ron_in_Conn (Jul 2, 2008)

Thanks, 30yearTech. I'm sorta betting on clogged filter screen, since there was a lot of junk in the tank from the hose rotting; it made a nice hole in the hose below the in-tank pick-up / filter so probably sucked in all kinds of crud.

I'll order a carb kit from Poulan and take a crack at it. Any key tips on working on diaphragm carbs? I've done float carbs from a big engine (though not for a long time), but never worked on elf-size carbs before.

Thanks again!


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## 30yearTech (Sep 14, 2006)

http://wem.walbro.com/distributors/servicemanuals/

You can download a service manual for your carburetor here if it's a Walbro or you can find info for Zama carbs at www.zamacarb.com


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## dawgpile (Apr 28, 2008)

Ron, the key thing to realize is the kit you'll get for your carb will contain several extra gaskets and a couple of pump diaphragms, and 1 metering diaphragm. This is because the same kit is used to service many carbs. Just take your time to match up the proper gaskets and pump diaphragm and throw away the remaining gaskets and pump diaphragms you don't use.

The other thing to pay attention to is the order of gasket vs diaphragm when you re-assemble. They are opposite depending on which side of the carb you're working on. On the metering side(generally the side with 4 screws holding the cover), the gasket goes against the carb body, and then the diaphragm(the metering diaphragm has the round metal part attached to the square rubber part). On the pump diaphragm side(generally the side with a single screw in the middle), the diaphragm goes against the carb body, then the gasket. You can see this in the last diagram of the IPL I posted. Finally, don't be alarmed if the pump diaphragm you remove from the carb is black rubber and the replacement is blue mylar. They are functionally the same! There is only 1 shape that will match!

As 30YT said, the filter screen is under the pump diaphragm. You can't miss it and you can easily clean it and the rest of the carb with 'carb and choke' spray with the red nozzle attached. My bet is it's clogged as well.

Let us know how you make out!


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## Ron_in_Conn (Jul 2, 2008)

Greatly appreciate all the expertise! It may be a little while 'til I get to work on it again, so wanted to thank you for your knowledge and support in advance.


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## ardenlester00 (Jun 5, 2010)

Same general problem as Ron. My weedeater is fairly new - but pulled up pile of junk into, through gas filter. Now, new filter, cleaned little filter in carb, cleaned diaphrams, etc. but still clogged somewhere. Where, inside the carb, could it still be clogged? Do we have to take out the adjustment screws on the side of the carb. Does it plug up somewhere inside? 

Thanks for this forum - I'm glad I ran up on it!

Dennis


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## macart52 (Jun 5, 2010)

Howdy fellers, Old mac here. Well I've been in the business for years and I never seen it fail with all 2 cycle carbs. When they been sittin around for some time, the carb gets full of shellac from the old stale gas. Now inside the carb, that y'all can't see, are all kinds of jets and air passages. Now when they're clogged, there is only one way to get it clean. No carb cleaner in the spray can will help. It has to sit in a carb bath over night. This solution is sold in 1and 5 gallon cans, with a parts basket. Now this solution is so powerful, it will eat the flesh from your hands. I haven't owned this stuff in years and I can't remember what it's called anymore. If you can find it, make sure you read the directions as it will melt any aluminum carb, if it sits too long in the solution. After it has set (per instructions), remove the carb with pliers and wash off completely with the garden hose, then blow dry with compressed air and reassemble. However before you do this, make sure you have the whole carb down to a bare block. It will eat neoprene gaskets, 0-rings etc! So imagine what it will do to your skin, let alone your eyes. So BE CAREFUL!!! People would bring in a mower with a Tech. engine into my shop, (years ago) and that was the only way to unclog them.

Hope this helped.

Ol Mac


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## BillieMc (Jun 11, 2010)

*Poulan weed eater gas lines*

Thanks Ron in Conn, I replaced my gas lines too. I could get the weed eater to run for a sec and then it would die. thanks to your post I've found I have a line running to the wrong place. I'm sure once I change it, I'll be up and running. :thumbsup:


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## hixdan (Jun 29, 2010)

this should probably have it's own thread, but i need an answer. my primer bulb fills with gas and then stops. no amount of pressure will get fuel into the carb. i've replaced all the diaphrams and am pretty sure i did it right. any suggestions?


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## 30yearTech (Sep 14, 2006)

hixdan said:


> this should probably have it's own thread, but i need an answer. my primer bulb fills with gas and then stops. no amount of pressure will get fuel into the carb. i've replaced all the diaphrams and am pretty sure i did it right. any suggestions?


Yes, I agree. This should have it's own thread.

What is it you have (Brand, Model, etc...) ?

Most primer's pull fuel through the carburetor and return to fuel tank. If the primer fills with fuel but will not expel the fuel back to the tank, there could be a blockage in the return hose, or a bad check valve in the primer body.


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