HT73 carburator cleaning

[yawning_dog]

Hi, I was wondering if anyone had any advice on cleaning the carb on an HT73 pole saw. It's sort of a weird carb- unlike any other stihl carb I've seen. It has a primer bulb and no H or L adjustment. My problem is that it totally bogs down and stops like it's not getting any gas when I rev it high or put it under a load. I took it apart, did the carb cleaner thing and put it back together and it won't even start now (it will with some gas directly in the carb). Undaunted, I took it apart again and this time removed the screen, which seemed to have accumulated a bunch of junk on the "back" side (between the screen and the needle valve). Anyway, I thought that was weird but it didn't seem like enough stuff to stop the flow of gas. But what does appear to be plugged (maybe) is the main jet. But I'm not sure how to actually clean it out or if the jet can be removed to be cleaned. Any ideas?

 

[yawning_dog]

Boil that carb!

Well, I thought I would post how this ended up. I took it apart a third time, and this time I boiled the main jet piece of the carb in water. To avoid my wife's wrath over cooking engine parts in her nice teflon coated pot, I cut a beer can in half, filled it with water and just plopped the carb piece in that. It took a while to heat up because there's not much surface area on the bottom, but when it got to boiling I kept it there for about 3 to 5 minutes or so. Then I just let it cool down, took it out to the garage and blew it off with compressed air. One thing I noticed was that there were a few lint/fibers that I was able to extract from the jet at that point. And I was also able to shoot carb spray through it which I hadn't been able to do previously. I put it back together and it fired up. I cut one small limb then, and it didn't show any sign of bogging down, but it wasn't really all warmed up yet either. Anyway, maybe the carb-boiling thing did it, maybe the carb cleaner did it, or maybe it's still hosed up. I'll find out more when I use it more! Hope this helps someone if you experience the same issue as I did.

--yawning_dog

 

[rmh3481]

Hi YD,
Im glad to hear that the carb cleaner worked. Many of the new carbs have fixed jets. Another style of fixed jet carb called a barrel carb comes on some of the new blowers. The barrel carbs have an adjustable needle similar to the old Lawnboy style carb with the altitude adjustment. Best thing to do is exactly what you did and that was a good cleaning. I hope you put the screen back in under the pump diaphragm? Depending on how many hours you have on that pole saw, maybe its time to replace the fuel filter that is in the tank? The pole saws also seem to sit for extended periods with gas in them, this isnt good. When your done using it, if it will be awhile before you use it again, drain out the gas. Keep all your fuel fresh and if possible out of the sun. Keep the cap on the can too.

Best wishes,
Bob

 

[yawning_dog]

rmh-

Yup, I sure did get that screen back in. I was really surprised to see all the debris where it was.

Well,I used the saw today and it seemed to work pretty well. So I'm going to call it "fixed". At least until the next time I use it and it doesn't start! Good idea about draining the gas in this one. Usually I don't do this with my saws, but in this case I probably will because I probably won't use it again for quite a while. I'm guessing the fuel filter is probably okay as the saw seems relatively new. But I'll give it a look at least to see if appears caked with crud! Thanks!