Snowblower surging! OMG I'm losing my mind!

redtom · Dec 14, 2019

I have my dads cub cadet 24in snowblower with a tecumseh engine. It always ran perfect and idled good. It has the 120 volt starter. It sat for a while before he passed
away and as usual the gas dried up and corroded a little in the carb. I cleaned tank and carb out and it will start right up but surges at full throttle and gets a
little better at lower speed but will only sometimes idle. Putting the auger in gear will smooth it some but not totally. It has no adjustment screws and I took the idle
jet out and cleaned it with a torch tip cleaner. I poked out all passages with the wire too and gumouted and blew the heck out of it at least 5 times. It has the
stupidest throttle lever spring hook up I've seen and I have no idea why its set up like it is. I can hold my finger against the governor arm and smooth out the hunting.
I moved the spring to different holes with no improvement. No one else has touched it before me. I am about to use the sledge to adjust the carb! I scouted the net and
tried most of the obvious fixes including sea foam. Is there anything im missing? Or should I just order a new carb? thy're pretty cheap now.

UncleTom · Dec 14, 2019

In the nut that holds the carb bowl on is the main jet. There is a small hole in the side of that nut. Take a wire from a wire brush and clamp it in a vice grip and poke it through it. The hole is very hard to see. The first time i found it i didnt believe there even was a hole there, but there is. Cured my problem. It was plugged very tight to where you couldnt see it. It took a very stiff wire such as the wire brush wire to poke through it.

guido · Dec 14, 2019

Hello redtom,

Some passages are impossible to clean. I just looke up a carb fkr a 9000 snow throeer with a B&S. Amazon bas one for less then $30 a d free shipping,

Guido.

whereswaldo · Dec 14, 2019

Absolutely right. Same thing happened to mine and I didn't think there was a hole there, either. It won't run right with that hole closed and that part is made of a metal that corrodes itself shut over time.

Billy NY · Dec 14, 2019

I've been wondering this same thing about my '02 vintage MTD gold model, 26" 8HP Tecumseh snow king engine. I don't recall these carbs being adjustable.

It runs like an engine wanting to run away, you cannot idle it and as I recall, the muffler turns orange. It sounds almost ok under a load, but when no load is on it, sounds like it wants to self destruct.

Funny thing is that nothing has ever been done to it, I've kept the oil changed, ran it season to season, starts on one pull. I have read the muffler glowing is probably a valve not closing. I'm wondering the diagnose and fix. Been as handy as a shirt pocket in regards to quickly clearing the minimal amount of snow until I can get on a tractor or now the backhoe.

steve_in_mo · Dec 14, 2019

IF your time is worth anything to you, just order the new Chinese carb
from one of the many online sources.

The replacement carbs are based on an older design that is adjustable.
That glowing muffler is from running too lean. The surging is also
from running too lean. I have reduced the surging on a Honda engine
with a similar Rube Goldberg governor linkage by adding another spring.
You should be able to find the carb for the 8 hp Tecumseh for less than $20.

redtom · Dec 14, 2019

Done it. Cross holes and hole in end poked out.

Russ from MN · Dec 14, 2019

I would definitely try some Seafoam, that's the first thing I do when an engine runs less than perfect, almost always solves the problem. I sure thought all those carbs were adjustable. No adjusting screw right on the bottom?

Dieseltech · Dec 14, 2019

Mine has always had a slight high speed no load surge since new. Soon as it enters snow it settles down and pulls fine.

Royse · Dec 14, 2019

(quoted from post at 19:25:51 12/14/19)That glowing muffler is from running too lean. The surging is also from running too lean.

I agree Steve.
Obviously the governor is working as intended, making it surge.
Get it enough fuel and it will run correctly. New carb, fuel line, fuel
filter or find the passage that was missed in past carb cleanings.

David G · Dec 14, 2019

A slight surge at WOT that settles down when loaded is not uncommon.

It is either a little lean or the governor spring is a little weak.

I would not worry too much if it holds its own under load.

Steve@Advance · Dec 14, 2019

Billy, the glowing exhaust is normal, especially on an engine with no timing advance.

If it starts that easy, it's in pretty good health.

grizz02 · Dec 14, 2019

I just posted a fix for my Tecumseh snow blower on tales mine was the mixture screw vibrating it self closed in 10 sec. I put Loctite on the threads

Janicholson · Dec 14, 2019

At the top of the carb, toward the engine or manifold, there is a (usually) covered screw. It has a small tin or plastic cap on it. Pry the cap off and take out the screw. it is an Idle jet and it is likely plugged up. Carb clean and a wire brush wire and all is well. Jim

Russ from MN · Dec 14, 2019

If your loosing your mind because a snowblower does't run perfect what's going to happen when you have a real problem in life? Put some Seafoam in it and take it out and work the $hit out of it!

MarkB_MI · Dec 15, 2019

Most likely it has a blocked idle passage, and on Tecumseh carbs they can be pretty much impossible to clean out. Buy a new carb and move on. Next spring remember to run the carb dry before you put it away.

Pycoed · Dec 15, 2019

Have a look at this starting at 01:00
https://www.youtube.com/watch?v=yCVdKjLWsmg

johnlobb · Dec 15, 2019

Get some Mechanic-In-A-Bottle. Wally world, Tractor Supply, Menards. Works better for cleaning out carbs than anything I've ever seen, and yes, I do like Seafoam. This stuff is better at cleaning.

Mutt and Jeff · Dec 15, 2019

Terryl 'll show ya
youtube

Mutt and Jeff · Dec 15, 2019

That loose part that can get stuck, I'd never known about that.

Me I just probe the mainjet and be done already.

redtom · Dec 15, 2019

Thank you for all the help, especially from those that didnt suggest doing what i already did as I said in my OP. I went ahead and ordered a new cheap china carb and will report back.

BarnyardEngineering · Dec 15, 2019

This is nothing against you. Just because you said you did something does not mean you necessarily did it correctly. People make mistakes. Especially when you are getting frustrated and do something "a million times" for example.

Unfortunately a new carb did not help when I had a similar problem. My snowblower with the H80 Tecumseh ran like yours from new out of the box. I always had to run with half choke or it would not idle, and as it warmed up it would begin surging when not under load. I never let fuel sit in it over the summer. I cleaned the carb "a million times." I poured quarts of mechanic in a bottle, seafoam, and berrymans b12 chemtool through it. Nothing changed. I lived with it.

Eventually I tried a cheap China carb off ebay. Still ran the same.

The only thing I found was that these engines have too small of a hole in the idle jet. People found success in drilling out the idle jet to the next size larger. I did not. I went and got a set of carb jet drills. Put one in my Dremel. Touched it to the tip of the idle jet and SNAP! Drill bit jammed in the end of the jet and broke off. Junk. Had to wait a week for a new jet to arrive in the mail praying that it would not snow. Did not try again.

claresnyder · Sep 30, 2021

(quoted from post at 04:27:10 12/15/19) I have my dads cub cadet 24in snowblower with a tecumseh engine. It always ran perfect and idled good. It has the 120 volt starter. It sat for a while before he passed
away and as usual the gas dried up and corroded a little in the carb. I cleaned tank and carb out and it will start right up but surges at full throttle and gets a
little better at lower speed but will only sometimes idle. Putting the auger in gear will smooth it some but not totally. It has no adjustment screws and I took the idle
jet out and cleaned it with a torch tip cleaner. I poked out all passages with the wire too and gumouted and blew the heck out of it at least 5 times. It has the
stupidest throttle lever spring hook up I've seen and I have no idea why its set up like it is. I can hold my finger against the governor arm and smooth out the hunting.
I moved the spring to different holes with no improvement. No one else has touched it before me. I am about to use the sledge to adjust the carb! I scouted the net and
tried most of the obvious fixes including sea foam. Is there anything im missing? Or should I just order a new carb? thy're pretty cheap now.

The new carbs are cheap but do not count on them being a solution. I installed a new "direct replacement" carb for an OHH55 Tecumseh on a Coleman generator because the float was sunk and it had been left for several years with stale gas. The new carb surged something awful until I removed the fixed main jet (bowl nut) and fixed idle jet and drilled each of them out 2 sizes (one at a time) until the hunt/surge went away both at no load and full load. Before drilling the jets I tried the jets from the original carb and the idle was too small and the main was WAY too big - - -

Snowblower surging! OMG I'm losing my mind!

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