Clean or rebuild the OEM carb. Stay far away from amazon and ebay Chinese cheapo's.
slomo
New Super Recycler sputtering issue.
- Thread starter Kjack138
- Start date
slomo
Did you get it fixed? What is the status of this well known sputter?
Saw one video where a guy said to remove the spark plug boot and reinstall it. Make sure you hear the click was his fix.
slomo
I’ve worked for Toro dealers since the early 80’s and I’ll say this. “GET A NEW DEALER”. The guy you are dealing with is part of the 1% of dealers who shouldn’t be allowed to sell anything. If there is no other dealer near by call Toro customer support 1-888-384-9939 and calmly explain your situation. Include the service bulletin number, plus have your model and serial numbers available and date of purchase.
I have the same problem with my Toro mower, model 21386, and B&S engine 104M020254F1. I notice the sputtering on bumpy terrain and inclines. Also, I discovered the gas tank on this mower has an air inlet on the side that spews gasoline into the air filter. I went ahead and replaced this with B&S part # 84004717, which fixed that issue but the sputtering continues.
Last edited:
I've seen mention of bulletin DSB-113/DBS-114, but does anyone have it, or knows what it says? Seems it involves replacing the carburetor.
The B&S on-line parts lists show the original part number, 596505. As my unit (Toro 20340 with the same engine) is beyond warranty, I'd be prepared to order and pay for the appropriate replacement if I could know what it is (e.g., part number).
I'm fairly convinced the problem is in the carb. There's distinct internal differences between the B&S 596505 and B&S carbs on similar non-SmartStow mowers that, on visual inspection, are outwardly identical; the differences, I believe, are related to the 596505 being able to store vertically without leaking fuel from the bowl. I suspect these differences might allow fuel in the bowl to enter the main carb passage (when the more is going over bumps etc), enriching the fuel mix and causing the sputtering, along with the reported puffs of smoke when the engine recovers.
The B&S on-line parts lists show the original part number, 596505. As my unit (Toro 20340 with the same engine) is beyond warranty, I'd be prepared to order and pay for the appropriate replacement if I could know what it is (e.g., part number).
I'm fairly convinced the problem is in the carb. There's distinct internal differences between the B&S 596505 and B&S carbs on similar non-SmartStow mowers that, on visual inspection, are outwardly identical; the differences, I believe, are related to the 596505 being able to store vertically without leaking fuel from the bowl. I suspect these differences might allow fuel in the bowl to enter the main carb passage (when the more is going over bumps etc), enriching the fuel mix and causing the sputtering, along with the reported puffs of smoke when the engine recovers.
That is a good observation POM. The "non-Smartstow" Toro model is 21462 and appears to have the same B&S engine: 7.25 ft-lb Gross Torque* Briggs & Stratton® Exi 163cc (engine model is 104M020010F1) From the B&S website, https://shop.briggsandstratton.com/pages/parts-lookup#, the carburetor part number is 594058.
B&S had/has a large number of 7.25, 163 cc., engines, but they are not all the same.
Been looking into which B&S engines use the 596505 carburetor and from an on-line parts store catalog found an "applicable to" list (these are B&S engine model numbers):
104M02-0130-F1
104M02-0131-F1
104M02-0249-F1
104M02-0254-F1
I then verified on the B&S site that these engine models do indeed use the 596505 carb.
In my searching I also came across mention of the carburetor being replaced by dealers according to a bulletin to fix the sputtering problem, but the context was the Toro 21387, which has the 190 cc engine. I suspect that DSB-113/DBS-114 might apply to that engine and not the 163 cc with the 596505 carb. In this regard, Toro seems to have only four "SmartStow" models that use the 163 cc. engine: 20339, 20340, 20355, and 21386, and interestingly, reviews of these models on the Toro website also mention the sputtering issue. I haven't yet found whether the 190 cc engine on the SmartStow 21387 uses the same carburetor, although I doubt it does. But the bulletin might explain what the problem is with the carburetor and that might also be applicable to the 596505. as both would be set up for vertical storage.
According to this B&S YouTube video the Mow and Stow/SmartStow engines incorporate a number of changes:
Only two would seem to possibly be related to the sputtering issue, namely, the revised carburetor vent, and the revised governor shaft. The video shows an older, metal carb, and refers only to changing the position of one vent. However, when I compare the plastic 596505 carb to plastic carbs used on non-SmartStow models, there's several vents that are different. This is what led me to think that the sputtering is related to the different carb. And if changing the carb on the 21387 fixed sputtering, the same change to a different carburetor might fix the problem some of us have with the 163 cc engine. As for the governor, I'm not aware of any internal changes that could affect governor operation in a way that bumps would cause the governor mechanism inside to initiate a momentary throttle change.
This B&S video is a good explanation of carburetors especially because it uses the plastic one as the model:
However, the venting in the 596505 is not the same. One visually obvious difference is the bowl area vent outlet. Instead of being terminated at a simple round plug (the "baffle") in the video at around 10:15, the 596505 has a horizontal extension tube. (See photos below). This extension, I presume, is designed to prevent fuel in the bowl from spilling out through the atmospheric vent when the engine is raised in the Stow position. But I suspect that when operating on uneven surfaces, the "sloshing" fuel in the bowl might enter this short, horizontal tube, restricting or blocking the tube, and as the video notes around 10:20, when the vent is blocked, "fuel is supplied to the engine for a very short time". So, momentarily, the engine is starved, and hesitates. The governor opens the throttle, and when the vent clears, the engine fuel supply suddenly surges, leading not only to recovery but also a puff of dark smoke due to the brief "rich" fuel mix. It's only an idea, until I learn otherwise . . .
Further info:
In regard to the venting, the B&S video points out that the fuel bowl vent is to atmosphere. That is correct for a non-SmartStow carburetor I have (799584). However, the SmartStow 596505 is different. Here's a comparison:
In the Normal configuration, both the "low speed air supply" and the "air mix for main jet" openings are after the air filter, with the "low speed air supply" also being after the choke. Both go to their intended locations inside the carburetor. As is apparent, the "fuel bowl vent" is separated from the carburetor inlet by the gasket, and actually opens out to atmosphere behind the air filter housing.
In the SmartStow 596505 carb, I found the "low speed air supply" and the "fuel bowl vent" passages to be closed internally, i.e., they don't go anywhere. (I could not see the low speed jet openings in the side of the venturi tubes in both carbs so that vent might not be needed.) Although the passage for the "air mix for the main jet" is the same as in the Normal configuration, in the 596505 it's also connected to passage going to the extended "fuel bowl vent" inside the fuel bowl. In other words, the fuel bowl venting in the 596505 does not originate out in atmosphere; it's after the filter.
Odd difference in the fuel bowl venting. Seems to me it would be affected by the throttle opening and the condition of the air filter. Could this be related to the sputtering that occurs when going over rough areas in the lawn?
In regard to the venting, the B&S video points out that the fuel bowl vent is to atmosphere. That is correct for a non-SmartStow carburetor I have (799584). However, the SmartStow 596505 is different. Here's a comparison:
In the Normal configuration, both the "low speed air supply" and the "air mix for main jet" openings are after the air filter, with the "low speed air supply" also being after the choke. Both go to their intended locations inside the carburetor. As is apparent, the "fuel bowl vent" is separated from the carburetor inlet by the gasket, and actually opens out to atmosphere behind the air filter housing.
In the SmartStow 596505 carb, I found the "low speed air supply" and the "fuel bowl vent" passages to be closed internally, i.e., they don't go anywhere. (I could not see the low speed jet openings in the side of the venturi tubes in both carbs so that vent might not be needed.) Although the passage for the "air mix for the main jet" is the same as in the Normal configuration, in the 596505 it's also connected to passage going to the extended "fuel bowl vent" inside the fuel bowl. In other words, the fuel bowl venting in the 596505 does not originate out in atmosphere; it's after the filter.
Odd difference in the fuel bowl venting. Seems to me it would be affected by the throttle opening and the condition of the air filter. Could this be related to the sputtering that occurs when going over rough areas in the lawn?
Thanks for this report, especially noting that changing the fuel tank resolved the fuel spewing, but didn't correct the sputtering. I also observed the same fuel spraying out of the tube onto the air filter and thought it could be enriching the mixture enough to cause the engine to hesitate. However, as that doesn't seem to be the case, I turned back to the carburetor.
As noted earlier, I have a concern about the long fuel bowl vent in the 596525 SmartStow carburetor -- see photos and comment at the end of post #17 above. To test this, I removed the long vent and in its place installed the round metal disk ("baffle") from a non-SmartStow carbs, as shown in the video). If my concern is correct, this should prevent the vent from being blocked by the fuel that is sloshing around in the bowl on rough surfaces.
A relatively short trial had no sputtering despite jostling the mower; but the sputtering would often show up only somewhat later during use, so I will test this more thoroughly over the next few mowings of the lawn.