# how to clear idle port in throat of Walbro



## wa5ngp (Aug 14, 2010)

I've got an old Walbro WT 324 that runs great at high speed on a string trimmer. As soon as I close the throttle it dies. Refuses to idle. I've tried cleaning everything that I can get access to.

I think the passage between the idle jet and the idle port in the throat is clogged. I say this as I took another Walbro (similar but not the same) and if I close off the high port and shoot carb cleaner down the idle needle hole the cleaner shoots out of 3 small holes in the throat. When I try this on the bad carb I cannot get the carb cleaner to flow out of those same holes. If I spray it into the throat ports it comes out of the other idle holes in the throat but not the idle jet hole upstream.

So my question is how to get that passageway cleaned out? Right now I have dribbled some carb cleaner into the idle jet hole and will let it soak overnight. I am tempted to push a fine steel wire from the carb throat holes down the passageway but I'm reluctant as I know I might pierce a small valve somewhere. Or is that a simple straight passageway from those throat holes to the bottom of the idle jet with no valves in between? I'm afraid high air pressure might blow out the power check valve in the process.

tks 
Don


----------



## glenjudy (Aug 26, 2006)

Pushing a fine wire down the idle progression holes will not harm anything. You might try to use carb spray down the hole from inside the carb throat.
If all else fails, there's a welch plug that covers the idle well that can be removed and you can see the idle passages.
the kit will have a welchplug in it.
hth


----------



## wa5ngp (Aug 14, 2010)

*clogged idle passage*

Thanks Glen. I have already tried spraying from inside the throat. There are 3 holes and when I do that I see cleaner come out the other 2. So the blockage is on the way to the adjusting screw. I have some very fine steel leader fishing wire that I may try pushing from inside the the throat now that you have said that I probably won't damage something.

I also have a can of Goo Gone. I may try a few drops of that stuff. Its pretty powerful stuff. Have you ever used that stuff?

I'm holding off on the removing the welch plugs for a while. I'm concerned my technique may not be precise enough to avoid damaging the the whole thing.

I'm learning a lot.

tks
Don


----------



## paulr44 (Oct 14, 2008)

Welch plug removal requires a special chisel, or a modified one of your own. Walbro part number 500-16 is indispensable when repairing small carbs.
One other note, that carb. is very cheap as far as carburetors go, only about $38 or less depending on where you get it.

Caution, many of these diaphragm carbs have a check valve for the high-speed circuit, to prevent bleed-out during idle. Carb cleaners containing xylene or similar caustic chemicals can deform (wrinkle or shrink) non-metallic parts so be very careful when trying to clean those passageways.

Service manual is free at http://wem.walbro.com/distributors/servicemanuals/
See the item #19 on page 2 for that check valve/nozzle. They're cheap too if you mess it up.
Paul


----------



## wa5ngp (Aug 14, 2010)

tks for the link.

I was thinking/afraid that the check valve might have something in it that doesn't like carb cleaner. I think that the idle port is so clogged up that the cleaner won't get there. OTOH once the port clears it will. So this is going to be an experiment that may result in the purchase of another carb. 

I know that the carb cleaner can destroy the primer bulbs.

I suppose those idle ports are the first thing to clog up since they are so small and after running hot the fuel probably evaporates in there leaving behind a residue. That must be the reason so many of these 2 cycle things have poor idle.

tks 
Don


----------



## paulr44 (Oct 14, 2008)

Some contributors here swear by the ultra-sonic cleaners. I've yet to use one so I can't comment, but it does make sense for cleaning gum deposits and dirt. I can't see it removing aluminum flashing or similar solids. Just had a new WT carb. I put on a saw less than 3 months ago crap out. Clean as a whistle inside...called our OEM tech dept., they figured casting flashing got into a passageway, and said to warranty it. Which is good as it's like a $125 carb. Good luck cleaning! Paul


----------



## junebug1701 (Jun 15, 2009)

Yes, count me as a new ultrasonic cleaner fan. I have a Mikuni carb off a Toro that I cleaned 2 times and installed a kit, and it still wouldn't run. After taking out the jets, nozzle, and needle and running them through the ultrasonic cleaner for 15 minutes it now runs perfectly. A new carb would have cost $180! You can get the ultrasonic cleaner from Harbor Freight for $25.


----------



## paulr44 (Oct 14, 2008)

$25? For that price, I have to concede and take the plunge. Plunge...get it? A lot cheaper than a 5 gal. pail of cold-soak caustic cleaner!
Thanks for the info.
Paul


----------



## glenjudy (Aug 26, 2006)

I got one of those cheap HF ultrasonic cleaners. My success rate on cube carbs has gone up considerable..
fwiw


----------



## junebug1701 (Jun 15, 2009)

glenjudy said:


> I got one of those cheap HF ultrasonic cleaners. My success rate on cube carbs has gone up considerable..
> fwiw


What kind of cleaning solution do you use in the ultrasonic cleaner? I've been using good old Windex with ammonia. Seems to work pretty good.


----------



## glenjudy (Aug 26, 2006)

I use a capful of Totally Awesome (Dollar General) de-greaser in warm, tepid water.
1) run USC for 2, 4-minute cycles.
2) Then spray externally with brake parts cleaner, and blow dry with compressed air 12-18 inches away from carb.
3) gently clear all passages with WD-40 (straw)
4) repeat 2)

My experience has been to be somewhat gentle in cleaning cube carbs, like Paulr, no harsh cleaners, and, no strong air blasts, so as not to damage any check valves, particulary ZAMAs with their idle check valves, they can't be replaced.
Thanks,


----------



## junebug1701 (Jun 15, 2009)

glenjudy said:


> I use a capful of Totally Awesome (Dollar General) de-greaser in warm, tepid water.
> 1) run USC for 2, 4-minute cycles.
> 2) Then spray externally with brake parts cleaner, and blow dry with compressed air 12-18 inches away from carb.
> 3) gently clear all passages with WD-40 (straw)
> ...


Sounds like a good procedure. So do you dip the whole carb into the cleaner? What about the rubber diaphragm, gaskets, and o-rings? Will they be OK or should they be removed first?


----------



## glenjudy (Aug 26, 2006)

It has to be totally disassembled, just the carb body goes in the cleaner.


----------



## wa5ngp (Aug 14, 2010)

I've been tempted to buy one of those HF ultrasonic cleaners for a long time. I wish I could come up with other reasons (excuses) to buy one.

That port is awfully small. maybe I should do some wavelength calculations to see if it makes sense.

For now the idle adj hole is still soaking in goo gone. 

Don


----------



## junebug1701 (Jun 15, 2009)

Another good reason to get an ultrasonic cleaner is for cleaning jewelry. My wife was very impressed when she saw how well it cleaned her rings. It also works very well on metal watchbands. Don't drop the watch in though--just the watchband.  




wa5ngp said:


> I've been tempted to buy one of those HF ultrasonic cleaners for a long time. I wish I could come up with other reasons (excuses) to buy one.
> 
> That port is awfully small. maybe I should do some wavelength calculations to see if it makes sense.
> 
> ...


----------

