Craftsman Mower Surge/Rough Idle

[GlockSpock]

Craftsman Mower: 917.288516

https://www.searspartsdirect.com/model/3o65abb09b-000247/craftsman-917288516-front-engine-lawn-tractor-parts

I've been troubleshooting this over the previous week or so.

So, today I rebuilt my carburetor with the factory Briggs & Stratton rebuild kit. I didn't immediately see anything that looked too off, the one thing I didn't replace was the o-ring on the jet as apparently my kit did not come with one.

Other things I have done this week include replacing the spark plug, new air filter, and trying a cheapium replacement carb from Amazon. If I recall correctly (I may be wrong), on the cheap replacement carb it seemed to idle better but immediately bogged down as soon as I hit any grass. The blades would engage just fine but the smallest amount of cutting would make it bog and sputter.

Right now, if I manually throttle it up more it seems to run/idle better. But right now I've got the throttle screw in all the way. I've experimented with the fuel/air screw so much by slowly screwing it in all the way in and out but right now is about the "best" I've got it.

I didn't open the welch plug although it does seem intact.

I'm at a loss. What is next?

The following link has a video exactly as it is when I left it today. Five photos of the carb itself before I rebuilt it. Do you think this is a factory Nikki carb or aftermarket? Most of the ones I have seen are actually stamped "Nikki" and "Briggs and Stratton". 

I bought the mower used, I suspect someone slapped a cheap $20.00 carb on it to "get it running". I've used it for over a year with generally no issue but this season I've noticed the surging/idle issue.

https://www.smugmug.com/gallery/n-vwXdVM

 

[FUJIMO]

13 minutes ago, GlockSpock said:

Craftsman Mower: 917.288516

https://www.searspartsdirect.com/model/3o65abb09b-000247/craftsman-917288516-front-engine-lawn-tractor-parts

I've been troubleshooting this over the previous week or so.

So, today I rebuilt my carburetor with the factory Briggs & Stratton rebuild kit. I didn't immediately see anything that looked too off, the one thing I didn't replace was the o-ring on the jet as apparently my kit did not come with one.

Other things I have done this week include replacing the spark plug, new air filter, and trying a cheapium replacement carb from Amazon. If I recall correctly (I may be wrong), on the cheap replacement carb it seemed to idle better but immediately bogged down as soon as I hit any grass. The blades would engage just fine but the smallest amount of cutting would make it bog and sputter.

Right now, if I manually throttle it up more it seems to run/idle better. But right now I've got the throttle screw in all the way. I've experimented with the fuel/air screw so much by slowly screwing it in all the way in and out but right now is about the "best" I've got it.

I didn't open the welch plug although it does seem intact.

I'm at a loss. What is next?

The following link has a video exactly as it is when I left it today. Five photos of the carb itself before I rebuilt it. Do you think this is a factory Nikki carb or aftermarket? Most of the ones I have seen are actually stamped "Nikki" and "Briggs and Stratton". 

I bought the mower used, I suspect someone slapped a cheap $20.00 carb on it to "get it running". I've used it for over a year with generally no issue but this season I've noticed the surging/idle issue.

https://www.smugmug.com/gallery/n-vwXdVM

 

I think that carb is a knock off brother. I agree oem are usually stamped somewhere. 

So the cheap Amazon carb idled fine but would bog under a load ? Did you adjust on it at all before moving on ?

Edited to add: sounds like the mixture is still "off" in the video. Like its still not getting a good balance.

Edited Wednesday at 11:57 PM by FUJIMO

[GlockSpock]

25 minutes ago, FUJIMO said:

I think that carb is a knock off brother. I agree oem are usually stamped somewhere. 

So the cheap Amazon carb idled fine but would bog under a load ? Did you adjust on it at all before moving on ?

Edited to add: sounds like the mixture is still "off" in the video. Like its still not getting a good balance.

I was pretty sure it is based off of how it looks. Also, the factory OEM needle allowed the float to completely bottom out today. I reused the "old" needle which seems to fully seat and the float allows a slight gap.

 Yes, from what I remember it idled fine but bogged under the slightest grass. But from what I could tell, it did not have a mixture screw:

https://www.amazon.com/dp/B0B6B6GBMZ?ref=ppx_yo2ov_dt_b_fed_asin_title

Maybe I'm wrong, but I think I decided to not really mess with it anymore. It needs to go back to Amazon. I suspect the jet hole may be undersized. Taryl Fixes All talks about this and I think it was him that "fixed" one of these by drilling the jet hole bigger.

Good news, I literally just purchased an OEM carb for this mower (I started typing this post, thought it out, placed the order, and then typed this). I liked this one because it still has the plastic piece on it, so I imagine that it hasn't been screwed with (pun fully intended). It may be gunked up or need rebuilding, but at least I should be able to trust it is all factory.

https://www.ebay.com/itm/187398740475

I may slap it on and see how it runs, or take the parts out of my carb and put in this OEM one.

Do you think first and foremost I have a carb issue still to handle? 

[GlockSpock]

Also, do you think it is too lean or rich? I suspect rich.

[Roaneman]

Check the intake manifold.  I've found that it can warp or bend allowing air in where it shouldn't. Specifically, if its plastic which many are.  When you remount the carb look closely at the mating surfaces between the carb and between the block.

Motor will fart and even backfire and have less power.

Not a great fix but I have used JB Weld to fill the gap.  The manifolds are expensive.

Good luck!

[FUJIMO]

2 minutes ago, GlockSpock said:

I was pretty sure it is based off of how it looks. Also, the factory OEM needle allowed the float to completely bottom out today. I reused the "old" needle which seems to fully seat and the float allows a slight gap.

 Yes, from what I remember it idled fine but bogged under the slightest grass. But from what I could tell, it did not have a mixture screw:

https://www.amazon.com/dp/B0B6B6GBMZ?ref=ppx_yo2ov_dt_b_fed_asin_title

Maybe I'm wrong, but I think I decided to not really mess with it anymore. It needs to go back to Amazon. I suspect the jet hole may be undersized. Taryl Fixes All talks about this and I think it was him that "fixed" one of these by drilling the jet hole bigger.

Good news, I literally just purchased an OEM carb for this mower (I started typing this post, thought it out, placed the order, and then typed this). I liked this one because it still has the plastic piece on it, so I imagine that it hasn't been screwed with (pun fully intended). It may be gunked up or need rebuilding, but at least I should be able to trust it is all factory.

https://www.ebay.com/itm/187398740475

I may slap it on and see how it runs, or take the parts out of my carb and put in this OEM one.

Do you think first and foremost I have a carb issue still to handle? 

 

2 minutes ago, GlockSpock said:

Also, do you think it is too lean or rich? I suspect rich.

Good move on purchasing an oem model. That may cure the whole issue. 

Yep, rich was my guess too.