Stihl 028 AV Wood Boss Carb trouble

[Wood Doctor]

I've put the carb back on but I wouldn't know what to look for to determine if the throttle shafts are sloppy (i'm not even sure I would know what the shafts are. I'm assuming it would be the shaft the throttle linkage attachs to.) the internal passages look clean to me but I'm not sure we're talking about the same passages and I have no idea what the metering level height is, let alone if it is correct. Yeah, I would like to verify someway whether or not the carb is bad before I plunk down cash for another one.



Yes, the intake ring just slid right out. For the life of me I can't figure out why it would be bent outta shape like it is. It's not like it has to be pried out or forced back in. I can't 100% blame it on the guy that worked on it because I don't know for a fact that it wasn't like that when I took it to him. But it sure seems suspicious being as it won't run as good as it did before he got it and he supposedly rebuilt the carb so he would have had it off and surely saw the shape of the intake. And as cheap as that part is I would have thought he would have replaced it. I'll try put the carb back on with the ring to check what happens.

Here are before and after pics. I'm not sure I did much good but it is better than it was. Trouble is now I can't get it to even start like it did yesterday. I removed the spark plug (which I bought new at the beginning of the summer) and wire brushed it. It didn't look too fouled to me and it is getting spark. The only time I can get it to fire at all is by spraying a little ether into the cylinder before reinserting the spark plug (and I did think beforehand, "I hope this is ok to do, maybe I should ask.") I did that a couple of times and it would fire off but immediately die.

Frankly, I think you did a good job straightening this out and reshaping it to fit. Looks like a guy grabbed it with a pair of pliers and then did a number on it while trying to remove it, not knowing that the metal was so thin. Fit it back in with a little oil to help seal it, reassemble, and then see if the engine still has the same running problems.

 

[bottomcat]

The metering lever is what controls the fuel level in the carb, if it's not set right it won't run properly... By the sounds of it it's not getting enough fuel. which would mean it's either not pumping the fuel, or the metering lever is set too low.. I am in a rush sand can't describe the procedure for that right now, perhaps someone else can take over?

thanks, there are probably posts here describing. i'll do a search.

I wouldn't make a habit of using ether. It has no lubricants in it. Much better to use a few drops of mix under the filter. Or a few drops on the filter.

Ted

yeah, i was a bit leary, just wanted to make sure it would fire off.

take a screwdriver and remove both covers on the carb and take some pics.

will do as soon as I get a chance. it may be next week before I can get back to it.

thanks for all the replies, help and advice. much obliged.
my bil's father is a mechanical wiz. he just lives about 3 hours from here. but before I start tearing into something that is over my head I will take it to him.

i forgot to mention that I took the muffler off. i didn't see a spark arrester screen but I sprayed the baffles down good with brake cleaner and then hit it a bit with a propane torch. I don't think it was clogged tho. I took the inner piece off too and couldn't see anything on the piston that was alarming but then I don't really know what I'm looking at. I couldn't really see the cylinder wall that well but it looked black not shiny from what i could see. Coulda just been that I wasn't getting good light on it tho.

edit: typos

 

[Rx7man]

Most starting fluids DO have lubricant in them... and besides there's probably plenty of residual oil everywhere to not need to worry about it.. I just found ether useless for gas engines, fuel works better.

The coating on the cylinder isn't always shiny.. it's usually a dull gray.. as long as you aren't seeing gouges in it it's probably fine

 

[bottomcat]

take a screwdriver and remove both covers on the carb and take some pics.

sorry i've been so long getting these posted. work and fishing been keeping me from doing due diligence.

 

[HarleyT]

There you go.....

 

[HarleyT]

Welch plug is loose.

 

[HarleyT]

You need to set it back in it's hole, and take a flat punch, and put a dimple on the top of the dome, so it expands slightly, and sits snugly in the recess of the hole. A dab of fingernail polish on the edge to seal.

http://outdoorpowerinfo.com/repairs/images/walbro_wt627/walbro_carb_wt627_welch_plug.JPG

 

[Nogoingback]

The gasket and diaphragm on the side of the carb where the fuel line is attached are wrong too. Diaphragm should first and then the gasket sitting on top.

 

[HarleyT]

The gasket and diaphragm on the side of the carb where the fuel line is attached are wrong too. Diaphragm should first and then the gasket sitting on top.

Good catch!!

 

[bottomcat]

You need to set it back in it's hole, and take a flat punch, and put a dimple on the top of the dome, so it expands slightly, and sits snugly in the recess of the hole. A dab of fingernail polish on the edge to seal.

thanks harley. i'm assuming that you mean to paint the dab of polish all along the rim of the plug where it rests in the hole.

and i'll be quite anxious about tapping that dimple into the plug. i'm assuming it will be ok to place the carb body in a bench vise for this procedure.

The gasket and diaphragm on the side of the carb where the fuel line is attached are wrong too. Diaphragm should first and then the gasket sitting on top.

thanks ngb. are these diaphragms and gaskets reusable or should i get new ones?

 

[bottomcat]

Carb is back together and on the saw. Saw will crank now but won't rev up very well. I cranked it with the breather off and with my hand on the throttle I could feel and sometimes see a fuel mist coming out of the carb throat. But since it is raining and dark I was in my garage and couldn't see very well. I ran it for a few minutes and it seemed like it might be about to come to life but by then my wrist was getting pretty wet from fuel and the garage was smoking up. I mainly just wanted to see if it would crank.

And rather than assume I put the carb back together properly here are pics of reassembly:

 

[Scott Kelly]

Pull the tank vent and see if she'll wind up then.. Spitting fuel back is usually a sign of a pressurized tank overcoming the needle and seat.

 

[HarleyT]

what are the mixture screws set at?

 

[drf255]

For my own education here,

The metering diaphragm always sits above the gasket on the metering side, and the pump diaphragm sits directly on the carb with the gasket between the diaphragm and pump plate?

 

[huskihl]

For my own education here,

The metering diaphragm always sits above the gasket on the metering side, and the pump diaphragm sits directly on the carb with the gasket between the diaphragm and pump plate?

Correct. (The one with the metal disc being the metering diaphragm )

 

[drf255]

Correct. (The one with the metal disc being the metering diaphragm )

Why thank you sir.

 

[HarleyT]

As a rule, the diaphragm is on the side of the smooth/polished surface.

 

[Brettl]

Carb is back together and on the saw. Saw will crank now but won't rev up very well. I cranked it with the breather off and with my hand on the throttle I could feel and sometimes see a fuel mist coming out of the carb throat. But since it is raining and dark I was in my garage and couldn't see very well. I ran it for a few minutes and it seemed like it might be about to come to life but by then my wrist was getting pretty wet from fuel and the garage was smoking up. I mainly just wanted to see if it would crank.

And rather than assume I put the carb back together properly here are pics of reassembly:

Good job on stickin with this, it can sure be frustrating. You'll have learned a lot by the time you figure this out though. Its great not to have to rely on shops. That idiot you took it to should have paid YOU. Anxious to hear how this turns out.

That clean and uncluttered work surface concerns me though.

 

[bottomcat]

Pull the tank vent and see if she'll wind up then.. Spitting fuel back is usually a sign of a pressurized tank overcoming the needle and seat.

I will do this today if I can figure out where it is.

what are the mixture screws set at?

Are those the two screws with the springs around them? I haven't adjust them at all. Not sure if the shop dude did or not.

 

[bottomcat]

Good job on stickin with this, it can sure be frustrating. You'll have learned a lot by the time you figure this out though. Its great not to have to rely on shops. That idiot you took it to should have paid YOU. Anxious to hear how this turns out.

That clean and uncluttered work surface concerns me though.

Thanks for the kind words. I have only been following the great advice and instructions I'm getting here. This place is great and I appreciate all of you taking the time to help noobs like me.

You'll notice that all those pics are close ups that don't revel the true background. No need to be concerned.