Learning to clean carburetor

Hello all, I'm new to this forum. I've spent the season over at snowblower forum, and this is my first year playing with and learning about small engines. Now that I've been learning, I figured I'd try doing some basic stuff on my Craftsman lawn mower (model # 917376395, B&S engine 126T02-1443-B1). I've had it maybe 2 years but never changed the oil or spark plug, drained the fuel, or cleaned the carb (I know, shame on me, but I'm trying to redeem myself now).

So this year after putting the snowblower to sleep, I drained the old gas on the lawnmower, replaced with Sta-bil-ized fuel, and changed the oil with new 5W30. Before all this, the lawn mower would start/stop two or three times or so, before finally starting and staying running. I figured what the heck, I might as well try to learn how to take apart and clean the carb (I am in no way a mechanically inclined person, but I do have YouTube!).

I took the carb out last night and ran wire through and sprayed carb cleaner through every hole I saw. I did not follow with compressed air or let it soak due to limited time. I was more interested in just learning how to take it apart and put it back together. This morning I ran the lawnmower again (~ 30 degrees outside) and it still exhibits some symptoms of starting briefly and then stopping a couple times, before finally staying running. The lawnmower has an auto-choke mechanism, so I have no idea if the carb still is a little dirty or if it's just a matter of being cold.

A couple questions:

I got some Gumout carb/choke cleaner on the carb bowl gasket. I didn't soak it but some of the runoff spray did come in contact with it. Probably a bad idea right? It seems a little more stretched than before.

What about the needle seat? I didn't have a carb tool handy to pull it out so I just ran a fine wire through it and then sprayed carb cleaner through it. Would carb cleaner damage the seat?

I am considering taking the carburetor out and apart again, and then soaking the parts in Pine Sol. Other than the bowl gasket, is there any part I should take out and not soak? Like the needle seat?

Finally, for those that have soaked carbs in Pine Sol, do you use 100% Pine Sol or do you tend to dilute it with water? And how long do you soak?

Also, although the start and immediately stopping symptom seems to be primarily a carb related issue, can this also occur with a fouled spark plug? I ordered a new one anyways, but I was just curious.

Thanks in advance. As you can tell, I have a lot to learn!

Yeah I would just drop off the bowl in order to replace that bowl gasket, and look closely at the bowl nut, that is also your high
jet, closely clean the holes in it, and reassemble it and run it, as long as it runs good when it warms up, as cold weather and off season fuel may be just what is causing this, spring and summer it will probably start better.

First, I would not soak the carb in Pine-Sal. You can use a 50/50 mix of good fresh gas and SeaFoam. 24hour soaking. Here is a procedure for rebuilding the carb. Post your engine numbers and I will get you the parts kit number you will need.

Needle and seat replacement

Remove the carb, and then remove the float bowl. Check the float bowl jet (which is the bowl screw) and make sure the jets both horizontal and vertical are clean and open. Tip the carb upside down and remove the float pin and float with needle attached. Look in the float needle passage and you should see the red float seat at the bottom of the passage. This is where a #5 crotchet hook would come in handy as you need to remove this seat. If you have no hook, but compressed air, you can blow through the fuel inlet and try to pop the seat out. Put your thumb over the passage to prevent the seat from flying who knows where. No air or hook try bending a stiff paper clip to dig the seat out.

With the seat out clean the passage way with carb cleaner. Now you must find a drill bit slightly smaller than the passage way, to be used to press in the new seat. Apply a very, very small amount of a very light lube to the new seat. 3-1 oil or lighter, to help seat it better. Carefully insert the new seat in the passage way with the rings on the seat down toward the carb body. Slowly and carefully force the seat down with the back end of the drill bit. Once it is seated, check to see that it did not flip and the rings are up. If everything looks correct, attach the new needle to the float and install with the float pin centered. It everything is correct, the float should seat level to the carb body, when looking at it upside down. If everything looks good reattach the float bowl, making sure that both the bowl gasket and the nut gasket seal properly. Reinstall on the engine and test unit. Remember to have patience and take your time. Good luck, but I don't think you'll need it.

PS: *On the side of some Tecumseh carbs you will find a plastic cover. *Under this cover will be an idle jet. *Remove it and check to see that theist is open both horizontally and vertically. *You should be able to push the old float needle wire through the vertical opening.

Rivets said:

First, I would not soak the carb in Pine-Sal. You can use a 50/50 mix of good fresh gas and SeaFoam. 24hour soaking. Here is a procedure for rebuilding the carb. Post your engine numbers and I will get you the parts kit number you will need.

Needle and seat replacement

Remove the carb, and then remove the float bowl. Check the float bowl jet (which is the bowl screw) and make sure the jets both horizontal and vertical are clean and open. Tip the carb upside down and remove the float pin and float with needle attached. Look in the float needle passage and you should see the red float seat at the bottom of the passage. This is where a #5 crotchet hook would come in handy as you need to remove this seat. If you have no hook, but compressed air, you can blow through the fuel inlet and try to pop the seat out. Put your thumb over the passage to prevent the seat from flying who knows where. No air or hook try bending a stiff paper clip to dig the seat out.

With the seat out clean the passage way with carb cleaner. Now you must find a drill bit slightly smaller than the passage way, to be used to press in the new seat. Apply a very, very small amount of a very light lube to the new seat. 3-1 oil or lighter, to help seat it better. Carefully insert the new seat in the passage way with the rings on the seat down toward the carb body. Slowly and carefully force the seat down with the back end of the drill bit. Once it is seated, check to see that it did not flip and the rings are up. If everything looks correct, attach the new needle to the float and install with the float pin centered. It everything is correct, the float should seat level to the carb body, when looking at it upside down. If everything looks good reattach the float bowl, making sure that both the bowl gasket and the nut gasket seal properly. Reinstall on the engine and test unit. Remember to have patience and take your time. Good luck, but I don't think you'll need it.

PS: *On the side of some Tecumseh carbs you will find a plastic cover. *Under this cover will be an idle jet. *Remove it and check to see that theist is open both horizontally and vertically. *You should be able to push the old float needle wire through the vertical opening.

Click to expand...

:thumbsup:

I'm no expert but I feel pretty comfortable taking a carb apart now and have some confidence I can make it better. I looked at some youtube vids...mostly a waste of time. The first couple of carbs were iffy. Am I gonna remember where everything goes? Now I just do it.
I've never heard about using Pine sol either til I saw a post mention it yesterday. I guess you won't have any germs in your carb

Some followup. Still doing experimentation on my lawnmower carb before I get the guts to do similar work on my more valuable snowblower.

I took the carb off and apart again (it gets easier and faster each time I do it!) and decided to soak it in Pine Sol. $3 for 48oz (lemon), plus 50 cents off with a manufacturer coupon. I used a small Torx screwdriver (maybe T7? T10?) and got the needle seat out. I did not take the emulsion tube out because I didn't have an appropriate tool to do it.

All in all I soaked the carb bowl, the actual carburetor, the needle seat, the float, and the main jet. I did not soak the main jet gasket or the carb bowl gasket. I used about ~ 15oz of straight Pine Sol, no dilution, and covered all parts to the top.

I started the soak at ~ 6pm and contemplated pulling the parts out before I went to sleep, but figured I've gone this far already -- might as well just soak it overnight! I brought it indoors so it soaked at room temp. This morning the bright yellow Pine Sol was much darker. There is darkening all over the exterior of the carburetor parts (aluminum?) which if I was smart, I could probably figure out was due to some form of oxidation or reduction. It appears to be purely cosmetic.

I lightly brushed the exterior with an old toothbrush just to see if any of the darkened color would come off (it did not), and then dried the parts off with paper towels, poked through every hole with a twisty tie wire, and blew through all holes and jets with compressed air. Re-assembled the carb and put it back on my lawnmower.

I cursed baby jebus after the lawnmower would not start, and then realized the spark plug boot was still off! I never pretended to be smart! After I put the spark plug boot on, voila, the lawnmower started on the first pull and stayed running, which it was not doing before. It was probably ~ 45 degrees at the time. Plus, the exhaust was lemon-y fresh!

Right now my snowblower runs with no choke, so I don't think I will take apart the carb this year. For now I'll just keep learning on my poor lawnmower. But if I ever do take the carb apart on my snowblower, I haven't decided if I will go the Pine Sol route, get an actual carb cleaner for a couple more bucks, or buy a cheapy utlrasonic cleaner (looks like $30-50 on Amazon, but I'm not sure which size I need yet to fit the carb parts).