Small engine troubleshooting...32cc Craftsman Zamba carb

[mpire]

So I have a 32cc craftsman trimmer.

Its coming up on its 3 year anniversary since I bought it.

I am having issues with keeping it going. It runs better with the leave blower and edger attachments but will run at 3/4 throttle just fine.

I broke down the carb, cleaned it and reassembled it.

Then I replaced the primer bulb and fuel lines, I am pretty sure the bulb was cracked. I am 99% certain the fuel line had a hole in it. Now its running consistently where I couldn't get it to run before. So I clearly had some clogging or something I guess.

So now I got it running, which is a good thing. However, when I am running the trimmer and I give it full throttle it dies pretty soon after that.

I have not adjusted anything but the idle screw.

I have yet to figure out how to take apart the exhaust so I can find the screen thing.

The plug is new. Doesn't appear to be all that bad...

Not sure how to modify the exhaust. Or to be honest, how to even get in there.

Engine says 50 hours, I may be at the upper limits. What does that mean? I need new seals and rings?

I have been searching, and I get the feeling its the same engine on every other trimmer on the market. I am searching the forum and will post any info I find that is relevant, however I would love to have a few pointers or any insights you can provide!

 

[KraftwerkMk1Jetta]

I would definately check the spark arrestor and muffler, and even the exhaust port for carbon build up. Also, check the gas cap vent. if it runs better with the cap loose then the vent on it is clogged. If that's all good, get a compression tester and see if the rings are worn out.

 

[scott37300]

There is a great small engine forum at www.perr.com. There are some really knowledgable small engine mechanics over there. Might want to try asking over there if you don't get much here.

 

[mpire]

Wait, I think its a Zama carb. I figure if you know these motors, you probably caught my error.

Ok, so I removed the spark arrestor screen and took some carb cleaner and a small brush to the exhaust port. I am not sure if it will make any difference.

Well, the screen removal makes a pretty big difference. Now I can run it up to full throttle and it doesn't die.

On another note, I can't put the air filter back on. If I do, it dies when I give it full throttle. So even though its a foam filter and is supposed to be cleaned and re-used, i guess I will have to replace it with a new one?

 

[mpire]

Ok, so screen removed and it just has a little slit for the exhaust.

How do I clean the muffler? Can I just soak it in some solvent or something for a day or so? The Muffler is not something that you can open up and take a look at.

 

[kburns]

To clean the muffler, first you have to remove it from the engine. Then pour a little gas in it & set it on fire. It'll put out black smoke like the old smudge pots. Use some common sense doing this so you don't burn down your house. I've cleaned mufflers this way for over 30 years with no problems.

 

[mpire]

Well, that seems easy enough. I will give that a try.

I wonder if I can fit a larger muffler to this thing and make it quieter.

I think that would take some custom fabrication.

I saw someone who had stuck a RC engine muffler on his weed wacker. I wonder if that would help...

 

[Motown]

Did you play with the carb adjustment screws at all? They take a special screw driver, which can be bought on Ebay.

 

[mpire]

Did you play with the carb adjustment screws at all? They take a special screw driver, which can be bought on Ebay.

Nope. I didn't want to mess with something I didn't know much about.

It runs great now with no air filter.

I removed the spark arrestor screen and that let it get to full throttle again.

I have to try the trick with setting the muffler on fire.

I am going to replace the fuel filter and the air filter tonight and see if it makes a difference. Regardless, I am happy enough at this point that I am returning the 4 cycle model I bought last night. I haven't opened the box yet.

 

[kburns]

After all you've done to it, if the carb is adjustable, you're probably going to have to adjust it whether you want to or not. If the jets are preset & not adjustable, there's not anything you can do.

The screw closest to the air filter is the high speed jet and the one closest to the engine is the low speed jet. Adjust the high speed jet so that the engine runs good at wide open throttle. Let the engine idle for about 30 seconds, then blip the throttle to see how well it speeds up. If it falters when you open the throttle, adjust the low speed jet until it doesn't falter. You might have to go through this routine a couple times to get it just right. It probably isn't going to take much adjustment, so turn the screws slowly. Clockwise leans out the jet, counterclockwise richens the jet.

 

[mpire]

Thanks kburns, will give that a try next time I have it apart. At the moment though, its running like new so I think I will leave it alone.

On a completely unrelated note, I picked up a couple pieces of pipe and a copper 1" threaded end piece. I sanded down the exhaust pipe coming out of the muffler on the mower and then I attached the copper end piece. I soldered it with some regular solder I had laying around. It was a snug fit before, used a mallet to get it on, but the solder definitely tightens it up so it doesn't rotate on me.

Added the pipe pieces and then this muffler I found at Lowes. Its for a larger mower of some sort. Threaded for 1" pipe thread. That being done, the only noise I hear now is the fan spinning. Its still fairly loud, but its not the popping noises I was hearing. It looks strange, but I think I am going to go with it. It was all under 10 bucks anyways, and I love to experiment.

Next up will be some ground effects to see if I can lower the sides of the mower to be closer to the ground while still maintaining a 4" cutting height.