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#483612 - 09/06/08 05:10 PM Weedeater FL20 with Walbro WT669 Carb
Harry123 Offline
first timer

Registered: 09/06/08
Posts: 1
Loc: Old Fort, NC
I bought this weedeater this spring and used it once. When I started it today it started right up but I couldn't get it to run out of choke. If I move the lever a litte toward half choke it ran great but would die when place in the middle position. Any ideas?
_________________________
Harold

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#483613 - 09/06/08 08:29 PM Re: Weedeater FL20 with Walbro WT669 Carb [Re: Harry123]
BillJeffy Offline
Don't Know Squat
Carpal Tunnel

Registered: 01/02/06
Posts: 9352
Loc: USA
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Does it (will it) continue to run if you press the primer bulb after moving halfway off-choke??F

Fuel supply problem or carb screwed up........
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Just Common Sense......
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err....I'm not a Doctor, but I'll take a LOOK ! !

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#483614 - 09/24/08 07:32 AM Re: Weedeater FL20 with Walbro WT669 Carb [Re: Harry123]
Tom12 Offline
newbie

Registered: 09/23/08
Posts: 3
I have this same identical problem with a WeedEater with a WT669 carb. Were you able to resolve the problem and if so, how?

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#483615 - 09/24/08 07:34 AM Re: Weedeater FL20 with Walbro WT669 Carb [Re: BillJeffy]
Tom12 Offline
newbie

Registered: 09/23/08
Posts: 3
Any suggestions on how to resolve the WeedEater with WT669 problem?

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#483616 - 09/24/08 08:14 AM Re: Weedeater FL20 with Walbro WT669 Carb [Re: Tom12]
JasonB Offline
Sharp -Shooter
Carpal Tunnel

Registered: 04/27/04
Posts: 14273
Loc: Cape Spencer, New Brunswick, C...
An engine that will only run on choke is being starved for fuel. There are a few possibilities.

Before disassembling anything, make good notes or take photos showing how the various fuel/primer and pulse lines are hooked up to the carb. Very difficult to sort out later.

If the eater is relatively new, then it's unlikely that the clunk filter is clogged, but it could be. Fuel should be able to flow freely from the supply tube.

The usual causes of the problems you're describing are too lean a main mixture setting, a clogged carb screen (inside the carb, usually cleaned or replaced as part of a carb kit), or a defective pump or metering diaphragm, or an air leak on the intake or crankcase of the engine. If the carb is quite new, a bad diaphragm isn't terribly likely, but not unheard of. Air leaks are relatively uncommon on engines that have not been disassembled.

(modern carbs need special tools to adjust the mixtures, should be available at a local small engine shop, or you may be able to modify them to accept a slot screwdriver, as in days of yore...)

Needle valve adjusting: the Hi one will be further from the engine, and the Lo will be closest to the engine. Most any Walbro carb'ed engine will start and run (very richly, tho) with both screws between 1.5 and 2 turns out from gently closed. Once she fires, she should run with the choke open, tho the engine will be down on power and smoke alot. Time to start tuning.

First, hold the throttle wide open, and slowly close the Hi needle (further from the engine). The engine will smoothe out and speed up. Note where the engine begins to sound smooth, and continue closing the needle (called leaning) until the engine begins to stumble and get rough again. Note this position, and then set the Hi needle to a little to the rich side of the middle of the 2 points you noted..... Hope that's clear...

Now, go to idle. Let the engine idle a little bit (30 seconds or so). Open the throttle and see how it performs. Probably it'll stumble, sputter, smoke and maybe quit. If so, lean the Lo needle a bit (closest to the engine) and try again. If it simply quits immediately, it's idle is lean and you'd need to open the Lo needle slightly. Repeat this until the engine accelerates from an idle cleanly to full throttle.

Because the idle jet has some effect on the main jet, after you get the idle working right, just revisit the Hi needle as described above to fine tune it. You want it set a bit towards the rich side of the 2 stumble points for best performance and engine life.

If that all doesn't go the way I described, my next suggestion would be to install a carb kit along with a thorough carb cleaning.

Good luck,

J
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er, somethin'....

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#483617 - 10/07/08 05:34 PM Re: Weedeater FL20 with Walbro WT669 Carb [Re: JasonB]
Tom12 Offline
newbie

Registered: 09/23/08
Posts: 3
I finally got around today to trying your suggestions. First, I installed a new carb kit for the WT 669 with no change in the problem. Still wouldn't run. Then I tried to find a "tool" on the Internet to "adjust" the carb. But, couldn't find a real one. So,....I used my Dremel tool with a metal cutting wheel to cut through the protective wall around the adjustment "screws" (if you can call them that) and cut a notch across them so I could use a screwdriver to adjust them. I started the adjustment by screwing them completely down (which took more than 2 turns). Then I backed each of them back out 1 and 3/4 turns (per your 1.5 to 2 turns suggestion). I reinstalled the carb, and took it outside to try to start it. I must say I was less than optimistic. But, holy cow, that sucker fired right up and ran perfect!!!!!!! It ran so good (like new) that I found no reason to do any further adjustment. Now, while the "screws" did not seem "loose", I can only presume that they had worked their way out over time enough to compromise the carb's performance. Thanks so much for the input.

And, by the way, a Dremel tool makes a great screwdriver notch cutter for Walbro carbs. I am really puzzled as why Walbro does not put a notch in the "screws" or at least make it easy to get a "tool" to adjust them if you want one.

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#483618 - 10/08/08 06:28 AM Re: Weedeater FL20 with Walbro WT669 Carb [Re: Tom12]
JasonB Offline
Sharp -Shooter
Carpal Tunnel

Registered: 04/27/04
Posts: 14273
Loc: Cape Spencer, New Brunswick, C...
Awesome! I know others here have used the dremel to gain adjustments. I work mostly on my own geriatric equipment and haven't had to yet, thus the lack of specificity in my post on that regard.

Walbro and most other small engine carb manufacturers have made needle access difficult to comply with EPA regulations. Seems the EPA doesn't realize that small engines require tuning to run correctly. They are trying to avoid people setting the engines excessively rich. From what I can tell, many are now set that way at the factory. I know my weedwhacker is a bit richer than I'd preferr it to be, but it works well enough that I haven't yet dug into it.

J
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er, somethin'....

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#483619 - 05/26/09 07:58 AM Re: Weedeater FL20 with Walbro WT669 Carb [Re: Tom12]
chrislipscomb Offline
newbie

Registered: 05/26/09
Posts: 5
Loc: West Virginia
I have the same carb on a WeedEater FeatherLite SST 25, and I had the same problem. I was looking into buying a carb kit when I stumbled across this post and what a find! You saved me time and money with the Dremel suggestion. I cut the shroud around the adjustment screws down far enough to reach the heads, then I cut notches into the screw heads, adjusted as directed in a previous post, started it up and performed some fine tuning. As it turned out, I needed to turn the low side out another half turn just to get mine to run off of choke. I was so excited I ran out and cut the yard! Thanks for the tip.
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The LORD is my Shepherd, I shall not want.

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#483620 - 05/26/09 08:13 AM Re: Weedeater FL20 with Walbro WT669 Carb [Re: chrislipscomb]
JasonB Offline
Sharp -Shooter
Carpal Tunnel

Registered: 04/27/04
Posts: 14273
Loc: Cape Spencer, New Brunswick, C...

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er, somethin'....

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#483621 - 05/28/09 02:54 PM Re: Weedeater FL20 with Walbro WT669 Carb [Re: JasonB]
Blaineg Offline
newbie

Registered: 05/28/09
Posts: 2
Loc: WI, Racine, Raymond
Hey guys! thanks for having your conversation about the carb adjustments! I have a Weedeater SS T25 (about 5 years old) and I'm having trouble with it (at this very moment) running on anything but full choke. I have taken the carb apart 2 or 3 times already and cleaned it Thoroughly. I replaced all fuel lines and sparkplug. I also started with fresh fuel and oil, and still no luck. I never removed the adj. screws. That's the only thing left I haven't done.

I will remove the adjusting screws (if I can) and blow out the ports, reinstall them and set to your specs. Hopefully that will be the answer!

Stay tuned for an update!!!

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#483622 - 05/28/09 09:53 PM Re: Weedeater FL20 with Walbro WT669 Carb [Re: Blaineg]
Blaineg Offline
newbie

Registered: 05/28/09
Posts: 2
Loc: WI, Racine, Raymond
Well, I did everything I said I would do and thanks to you it worked great!!! I had a little trouble finding something that would work with adjusting the mixture screws but with a little creativity I managed! (I called several small engine shops and no one had a tool for the splined screws) It started on the first pull and ran great! I still adjusted a little bit but really didn't make much of a difference. I was feeling so confident that I pulled out the Leaf blower that has been giving me trouble for the last 3 year and did the same thing to that and now that runs better than it did when it was new!

One note I would suggest is that you either replace or flex (bend and role) and clean ALL the fuel lines. What I seemed to notice was that the fuel must dry out in the lines when the muchine sits for a while, and when you try running it the dried residue breaks loose and plugs the screen in the carb. flexing the line thoroughly and running carb/brake cleaner through it will clean out all the residue in the lines.(or just replace the lines)

Thanks again! You saved me a couple hundred dollars by not having to buy a new weed eater and leaf blower!

Have a great summer!!!

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#483623 - 05/29/09 04:56 AM Re: Weedeater FL20 with Walbro WT669 Carb [Re: Blaineg]
JasonB Offline
Sharp -Shooter
Carpal Tunnel

Registered: 04/27/04
Posts: 14273
Loc: Cape Spencer, New Brunswick, C...
Good work, Blaineg! Not that hard a job once you get in there, is it? Satisfying when successful, too!

Old fuel oxidizes and becomes a varnish on any fuel component. Not a nice varnish, but a weak, gummy, sticky, smelly tan coloured gunge.

On any small engine I work on that has varnish in all the lines, I'll usually just replace those fuel lines rather than try to clean'em. I've felt it's 5 bucks well spent. Definately, though, not something to overlook!

Good tip!

J
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er, somethin'....

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#483624 - 06/01/09 01:51 PM Re: Weedeater FL20 with Walbro WT669 Carb [Re: Blaineg]
chrislipscomb Offline
newbie

Registered: 05/26/09
Posts: 5
Loc: West Virginia
I did not need to remove the screws, but I have had to fine tune each time I cold-start the trimmer. It is a great feeling to adjust just a little rich and have all that extra power under load!
_________________________
The LORD is my Shepherd, I shall not want.

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#483625 - 08/04/09 08:40 AM Re: Weedeater FL20 with Walbro WT669 Carb [Re: chrislipscomb]
OGBrewer Offline
first timer

Registered: 08/04/09
Posts: 1
Loc: Hastings, MN
I found that the 'applicator straw or tube' from a can of Great Stuff spray in foam insulation works great for removing the screws, in order to grind a slot in the heads for future adjustments. It fits very snuggly onto the screw, allowing it to be backed out of the carb.

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#483626 - 08/22/09 12:03 PM Re: Weedeater FL20 with Walbro WT669 Carb [Re: OGBrewer]
JoeBeck Offline
first timer

Registered: 08/22/09
Posts: 1
I have a weedeater featherlite that does the same thing. But my carb has only 1 screw which is plasic and orange sticking out of the carb. It is located between where the carb is marked L and H. Suggestions? Thanks

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#483627 - 06/23/11 12:52 PM Re: Weedeater FL20 with Walbro WT669 Carb [Re: JasonB]
HDWildBill Offline
first timer

Registered: 06/23/11
Posts: 1
Loc: Georgia
Thank you so much for the info. I followed the directions and my buddy's weedeater is working like a champ!

Buy the way a blue wire connector will work to get the adjustment screws out also.

Bill

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#483628 - 06/23/11 12:56 PM Re: Weedeater FL20 with Walbro WT669 Carb [Re: HDWildBill]
JasonB Offline
Sharp -Shooter
Carpal Tunnel

Registered: 04/27/04
Posts: 14273
Loc: Cape Spencer, New Brunswick, C...
Good! Thanks for posting!

J
_________________________
er, somethin'....

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#772457 - 10/09/13 10:36 PM Re: Weedeater FL20 with Walbro WT669 Carb [Re: Harry123]
Charlie_TX Offline
first timer

Registered: 10/09/13
Posts: 1
Thank You, JasonB for your 09/24/2008 reply to this post. I did not Dremmel the Carb Body, nor did I have the straw from the Spray Insulation. I stripped a 6" piece of the insulation from a section of a #10 electrical wire. I used a small drill bit to enlarge the opening of the wire, it would not quite go on the screw head, so I used a small amount of Aleene's Jewelry & Metal Glue to hold the insulation to the screw. I waited for two minutes, and was able to twist on the insulation, extracting the first screw, then the other. Using the Dremmel, I cut the notches. I screwed each back in, all the way, backed off 1 3/4 turns on each. Reassembled carb to engine, it fired right up and ran as it should.

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#772462 - 10/10/13 05:12 AM Re: Weedeater FL20 with Walbro WT669 Carb [Re: Harry123]
JasonB Offline
Sharp -Shooter
Carpal Tunnel

Registered: 04/27/04
Posts: 14273
Loc: Cape Spencer, New Brunswick, C...
Hey, wow, that's an old post! Good job on finding a way! Glad to have helped.

J
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er, somethin'....

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