9 hp Tecumseh surging/backfiring

[Tweeder]

Tecumseh 9 hp #143.039005

It surges and backfires at high idle with no choke. I smoothes out with one click of the choke so it's running lean. This is non adjustable carb, it don't look gummed up any suggestions?

 

[silver1]

Tecumseh 9 hp #143.039005

It surges and backfires at high idle with no choke. I smoothes out with one click of the choke so it's running lean. This is non adjustable carb, it don't look gummed up any suggestions?

Have a float? Needle Valve? bullet?

 

[Tweeder]

Have a float? Needle Valve? bullet?

It's all there from when it was new. Looking in the manual that came with the snowblower, it has a repair kit part number 632760. Not sure if it needs a rebuild or not, I've read of the same thing happening after a rebuild. I'm trying cleaning with carb cleaner and compressed air to see if that does it but what is causing it?

 

[Rivets]

The engine you have is an HMSK90-156543E. If it came into the shop I would be removing the carb and give it an ultrasonic cleaning. After cleaning, I would install a new float needle and seat before reassembling and installing back on the engine. Part number for the Kit is 631021B. You probably don't have an ultrasonic cleaner, so what I would do is disassemble the carb and remove all rubber parts and soak it in a bath of fresh gas and SeaFoam, 50/50 and then blow clean and rebuild. Attached is a manual which might help.

http://www.mymowerparts.com/pdf/Tec...P-4-CYCLE-L-HEAD-FLAT-HEAD-ENGINES-692509.pdf

 

[Tweeder]

The engine you have is an HMSK90-156543E. If it came into the shop I would be removing the carb and give it an ultrasonic cleaning. After cleaning, I would install a new float needle and seat before reassembling and installing back on the engine. Part number for the Kit is 631021B. You probably don't have an ultrasonic cleaner, so what I would do is disassemble the carb and remove all rubber parts and soak it in a bath of fresh gas and SeaFoam, 50/50 and then blow clean and rebuild. Attached is a manual which might help.

http://www.mymowerparts.com/pdf/Tec...P-4-CYCLE-L-HEAD-FLAT-HEAD-ENGINES-692509.pdf

Thanks for that. What's the difference between the kit part number you gave me and the one I have from my manual?

 

[Rivets]

The kit number you posted is a full rebuild kit, while the one I posted is a float needle and seat kit. No need to purchase a full kit, when you just need to replace the needle, seat and gasket. Some people say to replace everything, but I only replace the parts I need. It's up to you the direction you go.

 

[Tweeder]

I changed the seat and needle in the carb, cleaned and blew compressed air through all orifices and it's still surging. But now it does it under load which before it would only do it at high idle. I'm not sure if I got the governor arm in the proper position as I had it revving like crazy in the beginning but I have that under control. With that I wonder if it has something to do with the governor as I see that moving as well as the throttle as they are linked.

 

[Fish]

Remove the bowl nut again, look closely at it. Take a small wire and thoroughly clean all of the tiny holes in it, and look for a tiny one at the top of the threads,
clean it too.

 

[Tweeder]

Remove the bowl nut again, look closely at it. Take a small wire and thoroughly clean all of the tiny holes in it, and look for a tiny one at the top of the threads,
clean it too.

Oh, never cleaned that. Will do.

 

[Tweeder]

I cleaned the bolt on the bottom and it changed nothing, I'm thinking of adding sea foam to the fuel to help with cleaning.