Rough Idle - Dirty Carb or Something Worse?

[Tiger Small Engine]

I have to disagree on the effectiveness of seafoam. It doesn't always solve the problems but it has helped a lot more engines for me than it has done nothing for. Two mows isn't a very long treatment but because I need to sell this mower and finish it's video, I really don't have time to mow with it all summer to see if it works, especially when new carbs are $10 shipped. But I've had very good luck with sea foam actually DOING stuff, and by stuff, I mean making engines that run a little rough, run like they should.

If Seafoam were that good, why am I wasting my time cleaning all these hundreds of carburetors over the years and having the engines run great afterwards? Before I started running a small engine shop, I thought Seafoam was the bomb too.

 

[l008com]

Because you don't have time to use a customers machine for a few weeks to let seafoam work its magic. But as a homeowner, I have that time.
Also I'm not against cleaning a carb. Well, I am but not like that. Why bother cleaning when a new one is $10. But I'm just saying, it doesn't always fix things but it often will if you use it regularly. I put an ounce per gallon into all my power tool gas and I've had a lot fewer carb issues since I started doing that.

But yeah my boat has 3 carbs and they seem to have bad needle valves that let too much fuel in causing stalling at idle and a smokey mess when you are going slow. Seafoam isn't going to fix that.

 

[kbowley]

Because you don't have time to use a customers machine for a few weeks to let seafoam work its magic. But as a homeowner, I have that time.
Also I'm not against cleaning a carb. Well, I am but not like that. Why bother cleaning when a new one is $10. But I'm just saying, it doesn't always fix things but it often will if you use it regularly. I put an ounce per gallon into all my power tool gas and I've had a lot fewer carb issues since I started doing that.

But yeah my boat has 3 carbs and they seem to have bad needle valves that let too much fuel in causing stalling at idle and a smokey mess when you are going slow. Seafoam isn't going to fix that.

Good luck creating a proper running machine with the ten-dollar bill. Simply remove the carburetor and clean it thoroughly. It's an uncomplicated process, and you can Watch YouTube videos for guidance on cleaning. Allocate 30 minutes to fix the problem.

 

[SeniorCitizen]

Rough idle but seeming to run good at hi speed often points to a vacuum leak . Why ? There's more vacuum at idle speed causing a lean mixture more so than at hi speed . Ben there - dun that with a ford engine .

 

[l008com]

Hmm I guess I worded this poorly. I don't mean Idle in the traditional sense of the word, I mean lawnmower idle, which would be full RPM.
BUT that said, I replaced the carb today and the old one was missing an O ring that could have caused a vacuum leak, so that alone may fix the problem. It was late at night so I didn't get a chance to test it out but hopefully the engine is now at 100%!

 

[l008com]

GAH! Update: total failure!

The mower behaves the exact same way, rough starts and sputtering/misfiring while running!

I put the new carb in there, with the gasket that the old carb was missing. I also replaced the short little fuel line it has.

After mowing half my lawn with the same poor running, I went and grabbed my primary mower and swapped spark plugs. I hadn't replaced the plug in this machine because it looked like it was in great condition.

So I swapped the plugs and ran both mowers, no change. The honda mower still ran great with the TB's plug. And the TB still ran like poop with the honda's plug.

The gas tank looked totally clean and it was running on brand new gas.

What else is there? What else could cause poor running?

Edit: here's video of it running. It actually might be a little worse now, at least on startup. Once its running for a minute or two, it's about the same as before.

One thing that's weird, when it starts up cold, it runs extra bad. Almost like it might die out. It stays like that for a minute or so. Then suddenly it changes and goes into what I'll call it's "normal" mode, where it's still misfiring and running rough, but it does so at a much higher and steady RPM. It is totally useable in this normal mode, but it's definitely not running the way it should.

I'm not really sure where to go from here, any suggestions?

 

[Rivets]

I too was a great proponent of SeaFoam until about 10 years ago, but they changed their formula and now I wouldn’t recommend It to my enemies . Waste of money. Read this entire thread and there are three things I see. First the OP is hung up on his ideas and is poo-pooing suggests offered. Second, you need an OEM carb, period. Third, because you’re hung up on doing it your way, you’re missing a key element when solving a surging problem. At no point have you checked high end RPMs. Low RPMs will result in surging, especially when the carb may have a blocked passage way. If it is a blocked passage, I’ve found that unless I can get cleaner to move through it, problem will not be resolved. Read my signature.

 

[l008com]

Ok well i disagree with some of what you say, but this part I don't understand at all:

At no point have you checked high end RPMs. Low RPMs will result in surging, especially when the carb may have a blocked passage way.

I don't know what you mean here or what you are suggesting I do?

 

[Tiger Small Engine]

Ok well i disagree with some of what you say, but this part I don't understand at all:



I don't know what you mean here or what you are suggesting I do?

Let me spell it out in simple language. Either your carburetor is dirty and needs attention, or much less likely, you have an air leak. Try to open yourself up to people that have years of experience and are trying to help you. When I get phone calls from new customers, I have noticed that it is not uncommon that people are poor listeners. If you can get the mower running correctly, the sense of accomplishment is worth the trouble.

 

[l008com]

Doesn't it seem unlikely that the original carb was dirty, and the brand new one is also dirty? Seems like in this scenario where I've gone through two carbs, the air leak would be the more likely problem, no?