Runs great under load, but sputters without... - Snowblower Forum : Snow Blower Forums
Reply
 
LinkBack Thread Tools
post #1 of 32 Old 12-24-2016, 09:36 PM Thread Starter
Junior Member
 
Join Date: Dec 2016
Location: Poynette, Wisconsin
Posts: 14
Post Thanks / Like
Thanks (Given): 0
Thanks (Received): 0
Likes (Given): 0
Likes (Received): 0
Runs great under load, but sputters without...

Looking for some help... I have a Craftsman 9 hp 28" snow thrower, model 247.887900 made by MTD in 2007. Motor is Tecumseh. It always starts fine, but this year is running rough when NOT under load. I just replaced the carb and it's a bit smoother, but at times when not under load (crawling in F1 without auger running) it sputters and even will kill at times. It is sporadic and this is with choke off. There is some Sea Foam in fuel (had good luck with this in past) and fuel is ethanol free. New spark plug. Again, seems to run well under load, bigger the better. Any ideas? There is no fuel filter from what I can see and fuel is fresh.
KATfishing is offline  
Sponsored Links
Advertisement
 
post #2 of 32 Old 12-24-2016, 10:52 PM
Senior Member
 
e.fisher26's Avatar
 
Join Date: Nov 2016
Posts: 533
Post Thanks / Like
Thanks (Given): 6
Thanks (Received): 39
Likes (Given): 28
Likes (Received): 50
Does the replacement have adjustable bowl jet?


-efisher-
e.fisher26 is online now  
post #3 of 32 Old 12-24-2016, 11:14 PM Thread Starter
Junior Member
 
Join Date: Dec 2016
Location: Poynette, Wisconsin
Posts: 14
Post Thanks / Like
Thanks (Given): 0
Thanks (Received): 0
Likes (Given): 0
Likes (Received): 0
It looks identical to the OEM but the new non-OEM 640349 carb is an Everest carb.

I'm not sure the bowl jet can be adjusted in either of them... just unscrewed and cleaned. The other jet (for idle?) on the side with spring is the same with both also.
KATfishing is offline  
post #4 of 32 Old 12-25-2016, 08:06 AM
Senior Member
 
e.fisher26's Avatar
 
Join Date: Nov 2016
Posts: 533
Post Thanks / Like
Thanks (Given): 6
Thanks (Received): 39
Likes (Given): 28
Likes (Received): 50
Watch youtube on how to check valve clearances. When was last oil change?


-efisher-
e.fisher26 is online now  
post #5 of 32 Old 12-25-2016, 09:25 AM
Super Moderator
 
Kiss4aFrog's Avatar
 
Join Date: Nov 2013
Location: Hudson, WI
Posts: 9,137
Post Thanks / Like
Thanks (Given): 510
Thanks (Received): 681
Likes (Given): 3844
Likes (Received): 1478
Garage
to SBF KATfishing, fellow cheese head !!

It's best to check valves and anything else you can to make sure it's adjusted properly. If everything else checks out it might be running lean. Have you tried to apply the choke a click or two to see if it smooths out ??

.
Make sure the windows are up before the snow plow goes by !!

Please help keep the lights on by subscribing:
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Kiss4aFrog is offline  
post #6 of 32 Old 12-25-2016, 10:23 AM Thread Starter
Junior Member
 
Join Date: Dec 2016
Location: Poynette, Wisconsin
Posts: 14
Post Thanks / Like
Thanks (Given): 0
Thanks (Received): 0
Likes (Given): 0
Likes (Received): 0
Quote:
Originally Posted by e.fisher26 View Post
Watch youtube on how to check valve clearances. When was last oil change?


-efisher-
Changed oil one month ago. It was pretty dark. Might have missed last year's oil change but it wasn't run much with El Nino. Changed prior to using this year.
KATfishing is offline  
post #7 of 32 Old 12-25-2016, 10:43 AM Thread Starter
Junior Member
 
Join Date: Dec 2016
Location: Poynette, Wisconsin
Posts: 14
Post Thanks / Like
Thanks (Given): 0
Thanks (Received): 0
Likes (Given): 0
Likes (Received): 0
Quote:
Originally Posted by Kiss4aFrog View Post
to SBF KATfishing, fellow cheese head !!

It's best to check valves and anything else you can to make sure it's adjusted properly. If everything else checks out it might be running lean. Have you tried to apply the choke a click or two to see if it smooths out ??
Go Packers! And thanks for the welcome. I'll have to research how to check valves, including YouTube videos. On the old carb it ran better half choked. With new carb, runs best with no choke and under load is nice and smooth. I'm just scratching my head as to why once the auger is disengaged it sporadically spits, sputters and at time loses power. I read somewhere that Tecumseh gas tanks have a little built in screen in the bottom that acts as a built in fuel filter. Thought maybe I should drain tank and see if there is a blockage although that back to why is it running fine under load... perhaps it's sucking more gas and only runs lean when not under load? If it's running too lean and that's the problem, is my only option to drill the jet hole bigger if carb is nonadjustable? No problem starting. Fires right off on one pull. BTW - I know just enough to be dangerous, but I am a DYI-er because I hate paying someone else when I can learn to do it myself. Guessing I'm in the right crowd here
KATfishing is offline  
post #8 of 32 Old 12-25-2016, 11:03 AM
Senior Member
 
Join Date: Mar 2015
Location: Vermont's NorthEast Kingdom
Posts: 397
Post Thanks / Like
Thanks (Given): 0
Thanks (Received): 27
Likes (Given): 0
Likes (Received): 66
Since the OP's Tecumseh Engine has a non-OEM version of Carburetor 640349, which is on many Snowblowers, it should have the hidden Idle Restrictor Screw on it's side.

When allowed to collect fuel deposits in blocked passages of this screw, it causes chronic surging conditions, especially when NOT under load . . . . which sounds very similar to the problems with being encountered in the OP's machine.

Here's a Donyboy video showing the correction of this surging . . . . just in case it's the cause of the OP's surging and sputtering at idle:


I now find myself cleaning this valve about every 2 years !
Vermont007 is offline  
post #9 of 32 Old 12-25-2016, 11:21 AM
Senior Member
 
drmerdp's Avatar
 
Join Date: Feb 2014
Location: Northern NJ
Posts: 1,287
Post Thanks / Like
Thanks (Given): 6
Thanks (Received): 142
Likes (Given): 24
Likes (Received): 293
Regardless of the carb being new, the float needle doesn't always seat well at first.

I would physically exercise the needle and seat a few times then set the float height using a 5/32 drill bit before trying anything else.
drmerdp is offline  
post #10 of 32 Old 12-25-2016, 11:29 AM
Senior Member
 
e.fisher26's Avatar
 
Join Date: Nov 2016
Posts: 533
Post Thanks / Like
Thanks (Given): 6
Thanks (Received): 39
Likes (Given): 28
Likes (Received): 50
Ive bought a few ebay replacement carbs off ebay that have adjustable bowl jets just to have added adjustability. I like them for the cost of a rebuild kit


-efisher-
e.fisher26 is online now  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Snowblower Forum : Snow Blower Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in













Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome