Yard Machine FRUSTRATION!!!

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Originally Posted by chemman
Good luck! My carb is also a Nikki, but the bowl is metal. Hence, be gentle when "hitting" your carb with a hammer. Maybe aim for the area above the bowl, or use a screwdriver placed against the upper part of the carb and hit the screwsriver's handle with the hammer.


Those carbs are actually pretty pricey. I have roughly the same variant engine that takes a Nikki carb and it was well over $120. I was having issues with my old one and caved in and spent the money. Haven't had issues in several years.
 
the way to diagnose this is to get the fuel bowl filled, start the machine and after it dies, gently disconnect the fuel line. Then take off the bowl....is there fuel in there and at what level? If it is low, its almost for sure a stuck needle. It's been a while since I have done work on small engines. Can a person still purchase just a needle and seat? Perhaps a polish of the seat will do as other posters suggested. Diagnose! Diagnose! Diagnose! Don't be a "part replacer"
 
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I second the suggestion by chris142 to poke a wire through all orifices. Blowing air is sometimes sufficient, sometimes not. It is also worth taking the carb apart and cleaning all metal parts in acetone. Or just use carb cleaner spray.
 
This maybe a silly thought on my part... but i'll throw out there in any event - airlock in the fuel filter..??

My Lawnboy doest do squat until the filer is full..
 
Originally Posted by RyanY
I second the suggestion by chris142 to poke a wire through all orifices. Blowing air is sometimes sufficient, sometimes not. It is also worth taking the carb apart and cleaning all metal parts in acetone. Or just use carb cleaner spray.

+3
There is varnish plugging one or more of the jets and/or passageways. You need to physically poke a small stiff steel wire through ALL of the orifices (I use the wire inside of twist ties). Typically the main jet will be plugged with varnish such that you can't even identify that there is an orifice there at all, you can't see through it because you can't even see that it is there. On many carbs there will also be a small hole on in the side of the air/fuel mixing chamber that feeds fuel to the main jet. This is a case of knowing it is there from experience. After you are finished poking out all of the jets and orifices, use carb cleaner spray and spray it through every orifice and passageway making sure that it is coming out of the small holes in the carb throat next to the throttle butterfly.
 
+1 on poking the wire through the jets. Have a VW that would not idle. Did the cleaning regimine several times with no effect. Finally took a wire to it and there was a clear goo almost like lacquer in each jet. Put it together and still running good.
 
My knowledge of controlled fuel leaks is low, but the needle that goes through the float on mine was very corroded. This was a lawnmower that sat outside and filled the gas tank and carb completely with water. I would take it apart, clean it, then it would work 2 or 3 times and start on the first pull. But then it would just end up dieing and refusing to restart until I took it apart again.

I ended up cleaning it one last time then dumping some MMO into the gas tank at a very hefty level. Since then it has always started first pull and never stalled.
 
Like said, replacement carbs are under $20 online. I've replaced a few Briggs carbs with the no-name cheapy mail order carbs.

Problem is, your frustrations are only beginning. I see this MTD rider uses the MTD transmatic drive system. That's a real joy, especially on a machine that is left outside with a tarp over it. It's a belt and variator sheave drive system. The sliding sheave on the variator pulley hangs up due to it's slide bushing getting corroded and gunked up and you loose ground speed. You'll basically have no ground speed and painfully slow.
 
I fix small engines as a side business, and in many cases I end up replacing carbs if they don't work 100% after a cleaning or two. It just isn't worth the time and frustration along with possible problems down the road for the customer.

More expensive carbs or those that are hard to find get soaked and cleaned much more thoroughly in an effort to save them, but it seems with the ethanol in fuel you can get corrosion inside the tiny passages that you will likely never get out.

A lot of the snowblower carbs for example I can find online for under $20 shipped, so it doesn't make sense from a labor standpoint to clean it more than once or twice.
 
This year I changed those little O-rings wich are on the main jet (15+yrs old Tecumseh HMSK100)...what a change that was...first I tought that this engine valves got recesed...because it always started only after 2nd or 3rd pull...now it fires right away...

Maybe those shrank due to age!


DSC_1017.webp
 
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Originally Posted by philipp10
the way to diagnose this is to get the fuel bowl filled, start the machine and after it dies, gently disconnect the fuel line. Then take off the bowl....is there fuel in there and at what level? If it is low, its almost for sure a stuck needle. It's been a while since I have done work on small engines. Can a person still purchase just a needle and seat? Perhaps a polish of the seat will do as other posters suggested. Diagnose! Diagnose! Diagnose! Don't be a "part replacer"

Yes you can get carb rebuild kit on ebay....or on some online stores...

How to set... DonyBoy73 is a master!
 
This thread is totally FUBAR. We still haven't determined whether the engine in question is a Briggs & Stratton or a Tecumseh. Get that figured out before you guys start talking about carburetors. The original 1st post should've had some real and accurate engine numbers; that's how a small engine thread is supposed to start.
 
Originally Posted by das_peikko
This thread is totally FUBAR. We still haven't determined whether the engine in question is a Briggs & Stratton or a Tecumseh. Get that figured out before you guys start talking about carburetors. The original 1st post should've had some real and accurate engine numbers; that's how a small engine thread is supposed to start.

Nonsense. It doesn't matter what brand the engine is. The same scientific principles apply to all carbs (and engines in general, big or small), and the same problems affect all of them. Power Mechanics Troubleshooting 101... You can't figure out why something doesn't work unless you understand how it works.
 
Originally Posted by das_peikko
This thread is totally FUBAR. We still haven't determined whether the engine in question is a Briggs & Stratton or a Tecumseh. Get that figured out before you guys start talking about carburetors. The original 1st post should've had some real and accurate engine numbers; that's how a small engine thread is supposed to start.


It's a 13.5hp Briggs &Stratton. I did provide accurate numbers directly from the mower.
 
Originally Posted by wag123
Originally Posted by das_peikko
This thread is totally FUBAR. We still haven't determined whether the engine in question is a Briggs & Stratton or a Tecumseh. Get that figured out before you guys start talking about carburetors. The original 1st post should've had some real and accurate engine numbers; that's how a small engine thread is supposed to start.

Nonsense. It doesn't matter what brand the engine is. The same scientific principles apply to all carbs (and engines in general, big or small), and the same problems affect all of them. Power Mechanics Troubleshooting 101... You can't figure out why something doesn't work unless you understand how it works.


I bought a loaf of bread just for the wire. I'm going to give that a try and report back.
 
I took the carb off again. I soaked it in carb cleaner and used a wire to poke through everything.

The mower sputtered once and thats it. I pulled the plug and it was wet.

I quit. The new carb should be arriving in the next week or so.
 
Originally Posted by dja4260
I took the carb off again. I soaked it in carb cleaner and used a wire to poke through everything.

The mower sputtered once and thats it. I pulled the plug and it was wet.

I quit. The new carb should be arriving in the next week or so.

If the plug is wet you are getting fuel. Something else is wrong. Do you have spark? Does the engine have compression?
 
Originally Posted by dja4260
It's a 13.5hp Briggs &Stratton. I did provide accurate numbers directly from the mower.


I ran that model number through Briggs & Stratton. They say it doesn't exist.

[Linked Image]
 
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