Snowthrower sputters but won't start

Toro model 828 snowthrower with Briggs Stratton was given to me and I don't have an engine manual. After prime & choke it sputters for about 20 fires then dies. Trying different choke and throttle settings doesn't do the trick. The new plug gets spark and doesn't get wet. Tried with gas cap loosened and off without luck. Cleaned the carb (it didn't appear dirty). The brass injector tube spray holes are clean as well as needle valves and other passages. The metal float was empty so I assume it floats OK. I checked the float needle by turning the carb upside down and nothing flowed through, and does flow when right-side up. I don't know if this proves the float doesn't stick and valve works OK. The choke valve operates and closes. The throttle valve works. No obstructions in fuel line, intake, or exhaust. I don't know what are good carb adjustments. There's an upper adjusting screw that appears to provide bypass around the throttle valve... I assume this is the slow idle. It is backed-out 2 1/2 turns and I left it that way. I tried several adjustments on the lower fuel screw for the brass tube... 1, 1-1/2, 2, 2-1/2. I seemed to get the most sputters at 2-1/2 with the choke slightly open and full throttle. When I put the brass tube back I turned in all the way in (the tube, not the needle screw)... I don't know if that was correct. I don't work on engines much so I'm sure I missed something.

 

Hello cyev!

It sounds like you have the carb at a point where it should run. Have you tried dripping some gas into the plug hole and trying to start it? If it runs for a few seconds and then dies, you know it has a fuel related problem. I think more likely you have either a sheared flywheel key or too-tight valve clearances. Check the fuel sys. first.

 

Thanks for responding so quickly!

I agree that it seems like a fuel problem. I'm using fresh gas and I use the primer bulb to pump gas into the cylinder. If I don't prime, it doesn't kick at all. Maybe too little gas is getting from the carb into the spray tube? Is there some kind of check I can do? Interesting comment about valve clearance. I read another post about sticking valves. I haven't pulled the head to check. I can see where poor valve seating could keep it from creating enough suction on the intake.

Thanks again!

 

The check you can do is drop a bit of gas into the plug hole, then put the plug in and start it. If its not getting enough fuel, this should make it run for a second or 2. Then you know.

 

I finally got back to the engine today. It does run for a few secs after I drip some gas into the spark plug hole. I made sure the fuel line to the carb works by unscrewing the lower mixture screw until gas flowed. I reset the screw then backed it out 1-1/2 turns. It still wouldn't run more than about 10 slow putts. I know it has fresh gas because I got it with not gas and filled it with week old gas I used in my plow tractor. I took the carb off and checked the air passages... no clogs. There is no air filter so that isn't a clog problem. The exhaust muffler isn't clogged. The tube from the carb to the intake port is clear. I pulled the flywheel and the key is OK. I got a compression gauge and get 70psi. I went ahead and removed the head and the valves are not sticking and appear to close fully (no light shines through). The intake and exhaust ports are clear. I checked the valve springs and they look OK. There was never a position in the rotations when there was any clearance between the valve stems and tappets, but I couldn't see any way to make adjustments. I put everyting back together and the same result... at best 10 slow putts. I'm baffled. All I can think is that there is something wrong with the carb that I'm not catching.

 

Are you sure the choke valve is totally operating correctly? Try spraying wd-40 in the intake while the engine is running. Does the engine speed up and sound normal?

 

Remove the bowl srew, allowing the bowl to come off. Look at the sides of the bowl screw. There are 2 tiny holes opposing each other near the base, and ont near the top in a section that has no threads. This one is sometimes overlooked because it is so small, and when it is clogged, you cant see it well. It sounds to me like one or more of these are clogged.

Let us know.

 

I agree with Cheese. The bowl screw on the Tecumseh is a common problem.

I'm betting that my neighbor's putting and backfiring/blurping snowblower is this and when I take it apart, I will find a blocked screw .