Snapper 824 snowblower surges and dies, but only at full idle

   / Snapper 824 snowblower surges and dies, but only at full idle #1  

legbuh

Silver Member
Joined
Jul 22, 2010
Messages
185
Location
Southern MN
I have worked on a lot of small engines over the years as a hobby, so when my older neighbor said his blower wasn't running right, I offered to take a look. I assumed the carb was gummed up or something else.

I took the air jet out and cleaned it as well as the orifices. Then I took the bowl out and cleaned that and the main jet.

I set everything to spec for the idle mixture screw (not the idle, the air/idle screw) and main jet settings. I even took apart the fuel on/off lever and cleaned it up, put in fresh gas, changed the oil, cleaned the spark plug, etc.

It starts off great and low/mid idle and will sit and run forever. I took the time to adjust the idle mixture screw by turning it in until the engine started hesitating, then backed it out 1/2 turn. Even with the choke all the way off it just runs like a champ.

But, when I put it to full throttle, after about a minute it will start surging for a few seconds, then just die.

I tried with the fuel cap off, same thing. I tried hitting the primer when it was surging but nothing changed.

The only thing I didn't do was clean the needle/seat/float assembly. Because this seems like a fuel starvation issue, I am hoping that is the issue. But, I wanted to ask the pros if there may be something else I'm missing.

I thought about doing a compression test since it's a Tecumseh motor (never been a big fan), but it sure seems like a fuel issue.

Also, to me the fuel line coming out of the bottom of the tank, down into the fuel on/off valve, then up and through the motor to the carb seems like it would be fighting gravity to get fuel... I could add a picture if that helps, but the line literally goes down about an inch lower then where it goes back up and between the starter to the carb on the other side.

Thanks for any guidance!
 
   / Snapper 824 snowblower surges and dies, but only at full idle #2  
one of my chainsaws did similar thing, started fine, idle, but would bog out when I gave it the throttle. Turned out to be a crack in the fuel line that sucked in air when you gunned it.
 
   / Snapper 824 snowblower surges and dies, but only at full idle
  • Thread Starter
#3  
Ah... Good thought! I get to break out the smoke tester I use to find vacuum leaks!
 
   / Snapper 824 snowblower surges and dies, but only at full idle
  • Thread Starter
#4  
I found the issue. I've never seen a needle and seat where the needle was all metal, and the seat was a piece of rubber up into where the fuel comes out. That piece of rubber was disintegrated to the point where gas wouldn't flow fast enough, but it still sealed when the float went up.

Finding just that part would be impossible, so I'm ordering a new carb. 17 bucks. haha.
 
   / Snapper 824 snowblower surges and dies, but only at full idle
  • Thread Starter
#5  
I also found the new style Techumseh gas cap is limiting gas flow when it's tightened. I am digging into that issue as well.
 
   / Snapper 824 snowblower surges and dies, but only at full idle #6  
Had that issue on a previous toro mower. Apparently the gas cap wasn’t vented correctly from the factory so it was causing issues with fuel locking to the carb.
 
   / Snapper 824 snowblower surges and dies, but only at full idle #7  
Can you not just drill a 1/16 " hole thru the underneath portion of the gas cap, so the tank can vent properly and you won,t let moisture in because the vent is protected by the top of the cap ?
 

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