Pulsa-jet fixed-jet carburetor:

Hi guys, I have a Troy-Bilt Pony Tiller, which is powered by a 5 horse B&S engine. The carburetor is a pulsa-jet fixed-jet type. I have been able to start it, but if I try to move from choke to run it dies. I removed the spark plug, poured a small amount of gas inside and was able to keep it running a while longer, but never would really clear up and run. From what research I've done, I've decided to take the carb apart and clean it. I have questions that I hope you can help me with. I'm guessing I can't simply drop everything into a bath. I also would rather avoid having to completely dismantle it. If someone could offer some guidelines and tips to pull this off successfully, I would sure appreciate it.

 

That carb is a bit picky, but usually you can remove the fuel pump on the side of the carb ad remove the jet or mixture screw on the side of the carb, and spray carb cleaner through all the passages there, clean the jet, and reassemble. I prefer "next dimension" carb cleaner from advance auto parts.

 

Thanks Cheese, I'll sure give that a try. To be sure I'm on the right page with you though, the pump you are speaking of is the diaphragm pump, correct? And the mixture screw is directly across to the other side from the pump? And do feel reasonably sure this will fix it? Also, Will it pay me to submerge the entire carb in a parts cleaner bath, or could that damage the carb. If anyone else has other ideas, or if you agree with Cheese, please chime in.
Thanks.

 

I had an old rototiller that had one of those pulsa jet carbs and the thing that kept giving me trouble was the fuel pump diaphragm/gasket on the side of the carb. I would just always take that cover off, lube up that gasket with some oil and clean it between my fingers and put it back together. It would usually work fine for a while after that, but it was kind of a continual pain in the ass. I think it was mainly those little flappers on the diaphragm not sealing or opening when they were supposed to. Replacing the diaphragm would be a cheap repair. You might not be getting adequate fuel in the upper reservoir. (short suction tube)

Also make sure your needle valve is adjusted properly. If it needs to be choked to run, you might want to try turning that needle open another 1/4 turn and see if that helps. You can always turn it back if it doesn't help.

 

I would start by doing it without removing it, then if it doesn't work, take it off and soak it. Replace the pump diaphragm rather than fiddling with it, it's only a couple bucks.

 

I actually have already removed the carb, have ordered and received the rebuild kit, and plan to clean and replace the diaphragm this weekend. Thank you cheese and XSleeper for your input. I'd be kinda lost without your help.

A side note/different issue on another Pony tiller (same model same everything) I have an engine that seized at the crank shaft bore at the flywheel end. After looking at the schematic and parts lists, I was under the impression that there was a bushing in that bore (at least the parts list shows one) and when I asked the tech rep. at Briggs & Stratton she pretty much confirmed it. So I decided I would just press out the bad bushing and replace it. Well I ended up cracking the case and have decided there is no bushing. Now I am thinking of repairing the crack with J B Weld, boring the journal and re-bushing with an oil impregnated bronze bushing, rather then the aluminum bushing, which B & S offers. I can't imagine and aluminum bushing being superior to the O I Bronze bushing. Please share any insight you have in all of this and thank you in advance.

 

Hard to advise on a repair like that... it's not a standard type of thing. Any chance the crack caused something to go out of spec or bend? I would prefer a tig weld rather than just some JBweld on a crack, but it might work. With the low price of engines, I wouldn't rate spending a whole bunch of time on a repair like that. With the price of having the block re-bored, the bushing, and whatever other stuff you'll need plus time, it isn't worth it.

 

cheese, your perception is pretty sharp. Your "out of spec" comment also had my concern, with the shift in molecular structure at the crack, I am a bit concerned that everything will not seat perfectly. However, I am a machinist and would be able to do all of the work myself, except for the tig, and I have heard of some pretty amazing stories with regards to jbweld repairs. If you have other comments, please feel free, but if not I completely understand. Thanks again.

 

Well, being able to do it yourself is a plus. If you consider the time as learning time, or hobby time, then go for it. You won't have much money involved, so if it doesn't last long, you won't be out much more than time.