Repairing Walbro WA-59. Unknown potentially missing part

[Widget]

Hi guys,

I was recommended this forum from another engine repairer, though not chainsaw specific, I'm having an issue with a Walbro WA-59 carburetor, I thought perhaps it's used on chainsaws too.

I have an ECHO SRM-200DA & started cleaning the carb, a Walbro WA-59. I went to reinstall everything the other day with new gaskets, needle. screens etc & I'm stumped on one section (see pic). In the photo, it looks like something it covering the hole in the carb, perhaps a welch plug, but I can't find anything that would fit it among the spares nor did I receive any in my gasket or repair kit.

I've looked at diagrams from https://www.ereplacementparts.com/walbro-wa591-carburetor-parts-c-139716_142758_140714.html & also from WALBRO https://www.walbro.com/wp-content/uploads/2016/01/WAseries.pdf (which is pretty good) but still unsure if or what part is suppose to go there.

I've been told to just buy a replacement carburetor, I'd much rather fix it as the replacements are aftermarket, likely not as good & possibly a different design.
Is anyone familiar with this Walbro carburetor or perhaps have one lying around ? The closest (and only) reference material I've come across is in this video, where the carburetor is the WA version, but very very slightly different internally. The video shows one with the fuel inlet being a bent connection instead of the inlet that goes through the side like mine.



Hoping someone will have an idea, I've posted on multiple facebook groups and forums, but no one is too sure.

 

[Chevboy0167]

Should be this kit if you bought the entire repair kit... K10-WAT

https://www.ebay.com/itm/1110083952...fDuZRK5Hdz+dDCgE2WNq424azD|tkp:Bk9SR_SWtrGdYw

 

[Chevboy0167]

 

[Widget]

Should be this kit if you bought the entire repair kit... K10-WAT

https://www.ebay.com/itm/1110083952...fDuZRK5Hdz+dDCgE2WNq424azD|tkp:Bk9SR_SWtrGdYw



View attachment 1142605

Thanks Chevboy,
That's the repair kit I got, though those two welch plugs are too big for this carby. The tiny screen and retainer (#3 & #56 in the diagram) go onto the plate- circuit (#59). The only other parts I can think of are either #24 (plug-welch or cap - not included in the repair kit) or #57 (screen - check valve), which apparently #57 comes in the repair kit, but so does #56 which is also a screen-check valve. So perhaps there's 2 different sizes of check valves, but for some reason, both are not included in the kit. The check valve screen that comes in the repair kit doesn't seem to fit the check valve...
I did purchase this other kit (by mistake) https://www.ebay.com.au/itm/171018059606. It has what looks like, a 3rd welch plug. It's possible it could be an error with the editing of the image as it doesn't show the metering lever spring. Unfortunately I've asked the seller and he won't tell me.

 

[ZeroJunk]

FWIW. If you screw those needles out and spray carb cleaner in that inlet and it comes out in the little holes in the barrel of the carb there is no point in taking that welch plug out.

 

[Agrarian]

I have no first-hand knowledge but I don't believe anything goes there. It likely is a welch plug but one that is not meant to be replaced. All of the action in that area is the flapper valve sealing against the underside of the circuit plate until there is enough vacuum from the venturi (higher speed operation) to open the flapper valve and allow fuel to reach the main jet.

 

[Chevboy0167]

Can you measure the seat, (large hole), where the plug used to be seated? Digital or dial calipers would be best....

I have found a few new plugs for that series of carb but need a size first.

 

[Widget]

FWIW. If you screw those needles out and spray carb cleaner in that inlet and it comes out in the little holes in the barrel of the carb there is no point in taking that welch plug out.

Thanks Zero, I'll keep that in mind for future repairs . One thing though, I don't recall ever removing a welch plug . I've watched videos on the removal of them, and it seems you need a little bit of force, damaging it in the process. That's something one would remember, but it doesn't sound like something I'd do, or have ever done. The only other thing that it might b, if anything, maybe a cup-screen, similar to that of the larger 'fuel inlet screen' (#55) that comes in the repair kit.

I have no first-hand knowledge but I don't believe anything goes there. It likely is a welch plug but one that is not meant to be replaced.

Thanks Agrarian. I'm thinking that you may be right. I'm assuming if it were a replaceable/serviceable part, they would include it in the repair kit.

Can you measure the seat, (large hole), where the plug used to be seated? Digital or dial calipers would be best....

I have found a few new plugs for that series of carb but need a size first.

Hey Chevboy, I measured 4mm / 0.157" across. I've looked online but can only find the larger ones, the ones that come with the repair kit. There's also 'assorted' kits, but I'm unsure of they come that small.

Thanks again for the feedback, much appreciated

 

[SteveSr]

Thanks Zero, I'll keep that in mind for future repairs . One thing though, I don't recall ever removing a welch plug . I've watched videos on the removal of them, and it seems you need a little bit of force, damaging it in the process. That's something one would remember, but it doesn't sound like something I'd do, or have ever done. The only other thing that it might b, if anything, maybe a cup-screen, similar to that of the larger 'fuel inlet screen' (#55) that comes in the repair kit.


Thanks Agrarian. I'm thinking that you may be right. I'm assuming if it were a replaceable/serviceable part, they would include it in the repair kit.


Hey Chevboy, I measured 4mm / 0.157" across. I've looked online but can only find the larger ones, the ones that come with the repair kit. There's also 'assorted' kits, but I'm unsure of they come that small.

Thanks again for the feedback, much appreciated

FYI, Circuit plates and gaskets preceded welch plugs so it is unlikely that your carb would use both. That hole looks like access to the main nozzle. What happens if you spray carb cleaner into the hole? Where does it come out?

 

[Chevboy0167]

https://www.ebay.com/itm/2353539866...nrPgwqCNsy/Nh0GucgIeitNWBB|tkp:Bk9SR_r7sfSdYw

 

[ZeroJunk]

FYI, Circuit plates and gaskets preceded welch plugs so it is unlikely that your carb would use both. That hole looks like access to the main nozzle. What happens if you spray carb cleaner into the hole? Where does it come out?

He needs to look at what is under it. If the idle jets are not under it then it is doing some other function.

 

[SteveSr]

He needs to look at what is under it. If the idle jets are not under it then it is doing some other function.

Correct, You can see the 3 idle drillings that are covered by the circuit plate. It is also hard to tell which photos are from the OPs carb and which came from somewhere else - photo backgrounds are different.

 

[Woodslasher]

I wouldn't touch it. Put the carb together with the new parts and if i doesn't work right then chase down that little plug.

 

[Widget]

Hey guys, thanks for all the feedback, much appreciated

FYI, Circuit plates and gaskets preceded welch plugs so it is unlikely that your carb would use both. That hole looks like access to the main nozzle. What happens if you spray carb cleaner into the hole? Where does it come out?

Hey Steve, thanks for the info . I took some more pics for reference (see attached). The hole is connected to the smaller hole jsut above it and both are connected to the hi speed needle. The holes lead to the venturi & according to the Walbro PDF (linked in 1st post) it's for high speed. I took a photo with a light shining through. You can see the single Highs speed exit hole and the three idle holes.

https://www.ebay.com/itm/2353539866...nrPgwqCNsy/Nh0GucgIeitNWBB|tkp:Bk9SR_r7sfSdYw

Oh wow, awesome, thanks Chev . I'll have to chase down a supplier in Australia for it (international shipping is a killer), hopefully someone has it. Just have to remember Walbro 5/32.

He needs to look at what is under it. If the idle jets are not under it then it is doing some other function.

Hi Zero, the PDF (linked in 1st post) says the three holes are the idle passages. Looks like that hole is linked to the high speed needle and comes out into the venturi (see pic)

Correct, You can see the 3 idle drillings that are covered by the circuit plate. It is also hard to tell which photos are from the OPs carb and which came from somewhere else - photo backgrounds are different.

Hi Steve. All photos are mine, same carburetor, just taken at different times.

I wouldn't touch it. Put the carb together with the new parts and if i doesn't work right then chase down that little plug.

Hey wood, I might have to give that a try. If by chance it does require a welch plug (or other), what symptoms can I expect to happen?
Here's some more pictures. Sorry for the lower quality. I've edited them with a bit of info, hopefully it's helpful. If you need better, I'll retake them.

 

[stihltech]

You are not missing a welch plug. The circuit plate gasket and diaphragm cover those holes.

Kinds like knowing the insides of a Quadrajet. Been there, done that in the 80s.

 

[muddy42]

I wouldn't touch it. Put the carb together with the new parts and if i doesn't work right then chase down that little plug.

I agree with this approach. Generally I find less dismantling of the carb is often the safest approach. When I was less experienced I rendered a few carbs unusable by incorrect reassembly, compressed air or worse poking fuse wire where it shouldn't go. Now I simply replace gaskets and diaphragms, surface clean or soak the body and only spray carb cleaner in the H and L jets (no where else). 90% of the time this is all an old carb needs to get going again.

 

[fossil]

Quite a few of the WA series carbs show no welch plugs on the IPL. WA-59 appears to be one of them.

 

[SteveSr]

You are not missing a welch plug. The circuit plate gasket and diaphragm cover those holes.

Kinds like knowing the insides of a Quadrajet. Been there, done that in the 80s.

Take another look at the photos. It looks like he is missing the main nozzle and check valve. Hard to believe that the huge hole in the venturi is supposed to be the main nozzle.

Just found this in my archives... Does indeed look to be missing the main nozzle.

 

[stihltech]

The video shows the correct carb we a working on. I do not think the break downs do. Many versions over the years Early versions did not use a high speed check nozzle. Then there was a version with just a small check valve, then the brass valve we now regularly see.

 

[Widget]

You are not missing a welch plug. The circuit plate gasket and diaphragm cover those holes.

Kinds like knowing the insides of a Quadrajet. Been there, done that in the 80s.

To my knowledge, this trimmer is an older unit, maybe 70/80s, though I do wonder what it is in the picture. certainly looks like something is there

I agree with this approach. Generally I find less dismantling of the carb is often the safest approach. When I was less experienced I rendered a few carbs unusable by incorrect reassembly, compressed air or worse poking fuse wire where it shouldn't go. Now I simply replace gaskets and diaphragms, surface clean or soak the body and only spray carb cleaner in the H and L jets (no where else). 90% of the time this is all an old carb needs to get going again.

Normally I just replace the gaskets, diaphragms, screens, but have never touched a welch plug before. Never had an issue. I didn't know about the compressed air until recently, so I'll have to remember that next time, though iirc, I didn't use any this time. Carb went straight into the ultrasonic cleaner. Perhaps if something was there, it popped out & I didn't notice

Quite a few of the WA series carbs show no welch plugs on the IPL. WA-59 appears to be one of them.

The diagram from walbro shows a couple. https://www.walbro.com/wp-content/uploads/2016/01/WAseries.pdf but I believe this diagram covers multiple WA series as it shows primer bulb versions too.

Take another look at the photos. It looks like he is missing the main nozzle and check valve. Hard to believe that the huge hole in the venturi is supposed to be the main nozzle.

Just found this in my archives... Does indeed look to be missing the main nozzle.

Odd I don't remember seeing one there, nor seeing any part in the other parts lists/diagrams. I notice the file says '1994 series', perhaps it's a newer version to mine? I'm sure I read somewhere the trimmer was much older, maybe 70/80's.

The video shows the correct carb we a working on. I do not think the break downs do. Many versions over the years Early versions did not use a high speed check nozzle. Then there was a version with just a small check valve, then the brass valve we now regularly see.

The video's the only one that's very very similar, almost like it's 1 version off (older<>newer), but hard to tell because the inlet isn't recessed into the body, it's just a hole. I'm sure the version i had is 70/80s, so maybe it didn't have anything... but confusion as to what I'm looking at in the pictures I took lol

I did a quick search for the trimmer itself and found some new information.

https://www.jackssmallengines.com/j...trimmer-brushcutter-srm/srm-200da/part-list-2https://www.ereplacementparts.com/e...er-brushcutter-parts-c-35043_35180_35356.htmlhttps://www.partstree.com/models/srm-200-da-echo-string-trimmer-sn-001001-999999/part-list-2-1/
Three sources show the same diagram with no welch plug, but does show a 'nut' on the other side of the carb for some reason. Everything else looks identical. The serial on the trimmer says "0064383"

I think I might just put everything together and see what happens. Assuming I am missing something in that spot, what possibilities can I expect?