Lawnmower Carb cleaning - how to?

[spidey07]

Haven't used it in a few years. Put good gas in. Won't fire. The motor is working because if I spray carb cleaner directly into the carb it will run. Checked fuel lines, they're good. Spark plug looks good.

Is there anything made that you can soak the entire carb in? I'm thinking about just pulling it off and putting it into some kind of solvent.

Or do I have to disassemble it?

 

[wedi42]

disassemble the carb, wear eye protection, spray carb cleaner into all the little holes, dry with compressed air

at work we get a gallon of carb cleaner with a strainer to dip the carb into, it cost $50. you still have to disassemble the carb and remove any plastic parts.

 

[Evadman]

As Johngute said. Since it appears you are new to this, I will tell you that when you take the low and high speed bleaders out make sure to count the number of turns to seat them (this is what usually gets gummed up). The number changes based on brand, but BS engines are generally between 1 and 2, with 1.25 being the starting point IIRC. It's been a while since I did this.

 

[spidey07]

Originally posted by: johngute
disassemble the carb, wear eye protection, spray carb cleaner into all the little holes, dry with compressed air

at work we get a gallon of carb cleaner with a strainer to dip the carb into, it cost $50. you still have to disassemble the carb and remove any plastic parts.

aww crud. I think I have eye protection laying around. So how many little spings and screws are going to explode into a million pieces when I open it up?

 

[Safeway]

Originally posted by: johngute
disassemble the carb, wear eye protection, spray carb cleaner into all the little holes, dry with compressed air

at work we get a gallon of carb cleaner with a strainer to dip the carb into, it cost $50. you still have to disassemble the carb and remove any plastic parts.

Eye protection is a must. I'd wear gloves too. Aerosol carb cleaner is awfully powerful.

 

[wedi42]

it really depends on the brand
the eye protection is for the carb cleaner, not the springs.
the carb cleaner will go in one hole and out another pointed directly at your eyes.

 

[GuitarDaddy]

Sometimes it's more trouble than it's worth. The last time I had one like that I bought a new carb for about $30 and all was good. I would check to see what a new carb costs before investing too much time and effort.

 

[spidey07]

Originally posted by: Evadman
As Johngute said. Since it appears you are new to this, I will tell you that when you take the low and high speed bleaders out make sure to count the number of turns to seat them (this is what usually gets gummed up). The number changes based on brand, but BS engines are generally between 1 and 2, with 1.25 being the starting point IIRC. It's been a while since I did this.

Thanks. It's a honda. Maybe I can find the factory settings somewhere.

These are like the needles that control air/fuel mixture?

 

[spidey07]

Originally posted by: GuitarDaddy
Sometimes it's more trouble than it's worth. The last time I had one like that I bought a new carb for about $30 and all was good. I would check to see what a new carb costs before investing too much time and effort.

Brilliant! I'd gladly pay 30 bucks rather than muck with it.

 

[wedi42]

honda carbs are pretty simple and easy to clean, our cost is $50-60 for most models

there is only a couple of small parts, the needle and the spring.

 

[spidey07]

Originally posted by: johngute
honda carbs are pretty simple and easy to clean, our cost is $50-60 for most models

there is only a couple of small parts, the needle and the spring.

Cool. Thanks for the help. I'll give it a shot.

I HAVE to get it running today. Little buddy that mows my lawn moved and it's growing like wild fire.

 

[Evadman]

Originally posted by: johngute
honda carbs are pretty simple and easy to clean, our cost is $50-60 for most models

there is only a couple of small parts, the needle and the spring.

The spring isn't really 'springy' Unless there is something wrong with it, it is not going to go 'SPRONG' and embed itself in your forhead or anything.

the needle is a small 1/3" or so brass piece attached to the float. This is what lets fuel into the foat bowl. If you take off the bottom cup (generally a screw in the bottom that is 14mm) it will drain.

If there is no fuel in the bowl (none comes out when you release this plug) then the problem is with fuel getting to that point. So the needle valve is probably gummed up and plugging the inlet, or there is another obstruction somewhere.

If fuel comes out, then the problem is with the high/low needles. They have the smallest orifaces and can get plugged pretty easily. A grain of sand can do it, so old fuel that basicly turns into varnish can do it easily.

I must admit I have 3 honda small engines and have never had a problem with them, so I have never taken them apart. almost all of my knowledge is on B&S and Techumseh engines since that is what the neighberhood has. The basic principles are the same, though settings vary based on design and angle of the needle seats.

Originally posted by: johngute
it really depends on the brand
the eye protection is for the carb cleaner, not the springs.
the carb cleaner will go in one hole and out another pointed directly at your eyes.

Listen to this man, he is wize.
No mater where you spray it, the outlet is pointed at your face. It always works that way. That is why I do the same that he does, I soak the parts in cleaner.

 

[drnickriviera]

Maybe try some seafoam before taking off the carb.

 

[spidey07]

Well, man card revoked. Still won't start. Guess I'll have to take it or the carb in.

Removed carb - I took off the bottom cover and exposed the float, cleaner sprayed into the fuel inlet - pretty sure fuel is reaching the float. I sprayed every orifice I could fine. Never saw a needle valve after removing a few screws and spraying into these holes. You guys are right about it coming out other holes. :laugh: Did wear eye protection.

Spraying into the tube that dips down into the resevoir and cleaned that out. This looks like the jet that actually puts fuel into the throttle body. However there was a small "counter sinking" screw that went into this tube from the bottom. It looks like this can control how much fuel enters this tube because it appears to partially cover the only hoe in this tube that allows fuel into the jet (it wasn't a needle, more of a small grub screw). Almost looks like this grub screw was in so far it prevented fuel from entering this tube.

Oh well. Least I tried. It was definately gummed up but thought I did everything I could. May just pick up a service manual to try and get my man card back.

 

[Kadarin]

Originally posted by: spidey07
Well, man card revoked. Still won't start. Guess I'll have to take it or the carb in.

Removed carb - I took off the bottom cover and exposed the float, cleaner sprayed into the fuel inlet - pretty sure fuel is reaching the float. I sprayed every orifice I could fine. Never saw a needle valve after removing a few screws and spraying into these holes. You guys are right about it coming out other holes. :laugh: Did wear eye protection.

Spraying into the tube that dips down into the resevoir and cleaned that out. This looks like the jet that actually puts fuel into the throttle body. However there was a small "counter sinking" screw that went into this tube from the bottom. It looks like this can control how much fuel enters this tube because it appears to partially cover the only hoe in this tube that allows fuel into the jet (it wasn't a needle, more of a small grub screw). Almost looks like this grub screw was in so far it prevented fuel from entering this tube.

Oh well. Least I tried. It was definately gummed up but thought I did everything I could. May just pick up a service manual to try and get my man card back.

Hey, you made the effort. That alone is worth a man card...

 

[Evadman]

Originally posted by: spidey07
Well, man card revoked. Still won't start. Guess I'll have to take it or the carb in.

Removed carb - I took off the bottom cover and exposed the float, cleaner sprayed into the fuel inlet - pretty sure fuel is reaching the float. I sprayed every orifice I could fine. Never saw a needle valve after removing a few screws and spraying into these holes. You guys are right about it coming out other holes. :laugh: Did wear eye protection.

Spraying into the tube that dips down into the resevoir and cleaned that out. This looks like the jet that actually puts fuel into the throttle body. However there was a small "counter sinking" screw that went into this tube from the bottom. It looks like this can control how much fuel enters this tube because it appears to partially cover the only hoe in this tube that allows fuel into the jet (it wasn't a needle, more of a small grub screw). Almost looks like this grub screw was in so far it prevented fuel from entering this tube.

Oh well. Least I tried. It was definately gummed up but thought I did everything I could. May just pick up a service manual to try and get my man card back.

Screw that screw in all the way clockwize. count the number of rotations. Then screw it all the way out and clean it and the oriface.

If you put a thimblefull of fuel into the air inlet does the engine try to start? (take off air cleaner first)

 

[spidey07]

Originally posted by: Evadman
Screw that screw in all the way clockwize. count the number of rotations. Then screw it all the way out and clean it and the oriface.

If you put a thimblefull of fuel into the air inlet does the engine try to start? (take off air cleaner first)

This grub screw is what literally "screws into" the metal tube that exends from the middle of the throttle body. Taking out this grub screw and spraying into it, fuel drips into throttle body from "jet". There are a good 20 turns to get this grub screw all the way in. I think I backed it out 1.75 turns. This brass grub screw has a hole in the middle, this is filled with what looks like a tiny black rubber plug - I hope it is supposed to be sealed like that...the hole is so tiny through the center of the screw - 1.5 mm at most.

oh - fuel or cleaner sprayed into throttle body and motor starts and runs of that for about 5 seconds. That's what leads me to the carb. I'll have to double check the fuel lines just to rule that out, but even after sitting a few years the resovior was still "wet".

From here on out I'm going to perform regular storage procedures - turn off fuel and let motor run all the fuel out.

-edit-
the only needle valve I saw was near the idle stop screw, closer to the motor. Maybe THAT is what is blocked and THAT is what puts fuel into the throttle body. You can see the tip of the actual needle poking into the body. Maybe THIS is the one that is stopping me - I'll count the turns to stop, back all the way out and clean/reset.

Now if you ever need me to tune your nitro RC vechicle, I'll be there in a pinch.

 

[nonameo]

http://www.megasquirt.info/

Apply liberally.

 

[spidey07]

I think I found it!

http://www.lawn-mower-shop.com/carb3.htm

The "grub screw" is called the "main jet". If this is true then it sure shouldn't be clogged shut as I observed. Depicted as item #5 in this diagram.

 

[wedi42]

did you get the main jet out?
#4 in that diagram. it usually doesn't fall out, you have to push it down from inside the carb w/ a screwdriver.

there are lots of little holes you have to clean out. when you put it back in, screw it in all the way, no need to count the turns.

 

[spidey07]

Originally posted by: johngute
did you get the main jet out?
#4 in that diagram. it usually doesn't fall out, you have to push it down from inside the carb w/ a screwdriver.

there are lots of little holes you have to clean out. when you put it back in, screw it in all the way, no need to count the turns.

I'm talking about #5 - there is a hole through the screw, running perpendicular to the threads. If the grub (#5) were to screw down along a Y axis (up in this diagram), the hole is parallel with the Y axis.

In that diagram, #4 didn't come out and I didn't mess with it - if I can remove it and clean/soak it I will. #5 screws into the same tube the #4 and #5 do. #4 is labeled the nozzle, #5 the main jet. We may be onto something here. The carb isn't exactly as the one depicted but the overall stucture looks familiar with what I encountered.

What I'm trying to say is if I can get parts 4 and 5 and get them clean I should be good to go and get fuel into the body.

I'm on a mission now. I am NOT taking this thing in.

 

[imported_weadjust]

Usually the problem is part #11 in the digram. Over the winter varnish builds up on the needle and carb body causing the float to stick. You have to pull the float pin and remove the float to get the fuel inlet needle out.

Spraying the neddle and carb body with carb cleaner will not remove all the varnish. Try cleaning the hole in the carb body (hole for needle) with carb cleaner or goo gone and clean with a q-tip. Clean the sides of the needle with cleaner and a old tooth brush, steel wool, or very fine sand paper.

 

[spidey07]

Keep in mind this mower has not been used for a good 4-5 years (if not longer), with fuel just caking it up in the carb. This crap is like super glue! Hence if there is any powerful solvent I can use to soak for a few days. I can take the main pieces of the carb and soak - what to soak in? Carb cleaner doesn't make a dent into this "hard resin" like substance. Your word "varnish" is very appropiate - that's what it is like/is.

Thanks again for all the help. All I have to do is get fuel/air into the motor. Kinda like what a carb is supposed to do.

 

[imported_weadjust]

http://www.acehardware.com/product/index.jsp?productId=1451533&cid=

Gunk makes good produts. Kind of expensive for one carb cleaning. Old tooht brush and spary can of carb cleaner much cheaper.

I think the float is stuck or sticking. Will the bowl fill with gas?

 

[spidey07]

Originally posted by: weadjust
http://www.acehardware.com/product/index.jsp?productId=1451533&cid=

Gunk makes good produts. Kind of expensive for one carb cleaning. Old tooht brush and spary can of carb cleaner much cheaper.

I think the float is stuck or sticking. Will the bowl fill with gas?

Pretty sure the bowl will fill with gas. Will check.

The float moves freely and easily. Spraying fuel inlet gives copious amounts of fuel out #11 in the diagram.