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Hello all, new member here…
I just bought a used Swisher Trim-n-Mow (22") Walk-Behind String Trimmer
with a B&S series 650 motor

Or more specifically it’s a model 124T02-0129-E1

With a date code of 06121559 so I guess it’s about 12 years old

It was a non-running purchase but the price was right.

I started with a 5140B Tune up kit…. oil, spark plug, air filter (which was missing)

And of course a fresh tank of gas, but it would just sputter but not start, …. and it would only sputter after 4-5 shots of prime

Well I had a second person pull the cord while I continuously and briskly pumped the red primer plunger after it sputtered and I was able to keep it running for several minutes but as soon as I stopped priming, the engine would stall immediately.

So what do you think? I’m thinking a carburetor problem but what specifically?

I pulled the bowl and it was surprisingly clean, fuel flowed when the float dangled and stopped when lifted

Ok I know that carb very well and can rebuild them blind folded....... When you took the bowl BOLT out that is your main jet.......

Take it out again and there is a hole on the top that meets the 2 holes on the sides of the bolt near the head of it pass a stripped bread tie in all three of those holes then spray with carb clean.....

Make sure those holes are clean and you see thru them... Put it back on and fire that puppy up ............

Let us know Mon Ami ~!~!

A lot of people call that a bowl NUT we know it as that also ..........

I blew through it while i had it out, air passed through but i did not clean it well, just blew through it and figured since it was not blocked it must be ok

will try that tomorrow

Like I said there is a hole on top of it..... If that is clogged no gas can be sucked up from the side holes up into the tube.....

Was there gas in the bowl when you took the bolt out ????

Boudreaux In Eunice La. said:

Like I said there is a hole on top of it..... If that is clogged no gas can be sucked up from the side holes up into the tube.....

Was there gas in the bowl when you took the bolt out ????

Click to expand...

yes the bowl had fuel in it, when i starting loosening the bolt fuel started pouring out

once the bowl was removed i blew in the hole in the bolt and air came out 1 or 2 of the side holes

Check that bowl nut again and clean it well..... If that don't do it then you need a carb kit and a complete tear down and a soaking in a carb bath........

Let us know Mon Ami ~!~!

Having the same issue. Will this engine run without the backpressure of the crank case vent? The air filter housing is in the way of everything I'm doing and I'd like to just get it running before putting everything back on. I know that vent feeds into the carb bowl and pressurizes it, but thought it may suck enough air in to run with the cover off (so vent hose, filter, and filter box casing removed from carb). Once it runs longer than 1 second I'll button it up.

One1 said:

Having the same issue. Will this engine run without the backpressure of the crank case vent? The air filter housing is in the way of everything I'm doing and I'd like to just get it running before putting everything back on. I know that vent feeds into the carb bowl and pressurizes it, but thought it may suck enough air in to run with the cover off (so vent hose, filter, and filter box casing removed from carb). Once it runs longer than 1 second I'll button it up.

Click to expand...

Yes it will run without the tube connected I do that all the time when I work on them...... You just might have a loose or broken intake tube..... The intake tube comes from the carb under the coil and 2 bolts hold it to the block..... Your O ring behind the carb may be an issue also ..........

If you have the air box still attatched that means you didn't take the carb off and clean it well.. Right ??

I was having idle issues running WITHOUT the airbox, but a second cleaning of the top hole in the main jet seems to have fixed it. Curiously however I didn't get the upper rpms i was looking for tuning until I force fed the carb bowl to simulate the vaccume it would get with the airbox on.

https://s31.postimg.cc/wl1l24dqz/20180426_180718.jpg

So thats how I solved that. No starvation of gas in the throat of the carb that way.

I’m willing to bet that your float level is too low, caused by a float seat which is swelled during storage with old fuel in the system. I see this problem almost every day. My solution is to clean and rebuild the carb, with Briggs part number 398188. Here is the procedure I use.

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.


I would either give the carb a good 24 hour soaking or have it ultrasonically cleaned at this time.


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. Next check to make sure that the float does not have any liquid in it. If it does, replace. 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 the jet is open both horizontally and vertically. You should be able to push the old float needle wire through the vertical opening.

Boudreaux In Eunice La. said:

Ok I know that carb very well and can rebuild them blind folded....... When you took the bowl BOLT out that is your main jet.......

Take it out again and there is a hole on the top that meets the 2 holes on the sides of the bolt near the head of it pass a stripped bread tie in all three of those holes then spray with carb clean.....

Make sure those holes are clean and you see thru them... Put it back on and fire that puppy up ............

Let us know Mon Ami ~!~!

Click to expand...

Original Poster here....

sorry it took a while, well this morning i went out and fired it up, still had to continuously pump the red primer bulb to keep it running

next i pulled the carb and and cleaned with carb cleaner paying special attention to the 3 holes in the bowl bolt (main jet) i used the wire from a bread tie to clear the holes and sprayed em again

reassembled and it started on the first pull and stayed running without prime, but....

the RPM's sound a bit low, sounds like it is about mid throttle for a Briggs, furthermore it was surging a bit

i could see the black plastic thing on the top of carb (choke control?) moving back and forth with the surges

when i put my finger on the black plastic thing preventing it from moving the surging stopped

any idea how to stop that and to ensure full power is available?

thanks

No choke on that one... You have primer that takes the place of a choke.... Your carb is still dirty or you have unmetered air getting in somewhere. Intake tube leaking at block... Or the o ring behind the carb is bad or missing....

Did you take the carb off ??

azsportpilot said:

Original Poster here....

sorry it took a while, well this morning i went out and fired it up, still had to continuously pump the red primer bulb to keep it running

next i pulled the carb and and cleaned with carb cleaner paying special attention to the 3 holes in the bowl bolt (main jet) i used the wire from a bread tie to clear the holes and sprayed em again

reassembled and it started on the first pull and stayed running without prime, but....

the RPM's sound a bit low, sounds like it is about mid throttle for a Briggs, furthermore it was surging a bit

i could see the black plastic thing on the top of carb (choke control?) moving back and forth with the surges

when i put my finger on the black plastic thing preventing it from moving the surging stopped

any idea how to stop that and to ensure full power is available?

thanks

Click to expand...

Yes,
Clean the carb as in the previous post by Rivets and replace the needle & seat.

Boudreaux In Eunice La. said:

No choke on that one... You have primer that takes the place of a choke.... Your carb is still dirty or you have unmetered air getting in somewhere. Intake tube leaking at block... Or the o ring behind the carb is bad or missing....

Did you take the carb off ??

Click to expand...

Yes I had the card off when i cleaned it at the workbench, I re-cleaned the main jet bolt and made the mounting bolts snugger and it seems to run ok now, ran a full tank of gas through it

thanks to everyone for all the help

Thank you for the solved reply ..............