Trouble with a Carb for 55 husky

[dumbarky]

I was wondering if any of you guys have swapped the WT 170 carb for something else or found a substitute for it. I have a 55 Husky just rebuilt the engine, new piston and ring, wrist pin bearing gaskets the like. Even rebuilt the carb but still have a dead spot in the lower to mid rpm range. Set the carb L at 1 1/4 out and the H at 1 1/4 out, but doesn't run very well. Opened up the L circuit maybe another 1/4 total runs but still not what I like. I am afraid to mess with the High circuit much I am guessing it should not be closed more than 1 full turn open. I am guessing the problem may lie with the fuel pump side of the carb. I replaced it but the carb kit I used was made the same but with a different type material. Any help here would be appreciated. :deadhorse:

 

[dumbarky]

Looking for help

Took carb apart again. Somewhat better but still having trouble. Adjusted carb to run well, but after less than 10 minutes run time she starts getting same symptoms again. Wondering if I may have a leaking seal on crankshaft or jug gasket, crankcase gasket. It all seems to be affecting the low circuit of the carb any comments.

 

[hexen71]

check the impulse line I had my 51 do the same thing

 

[robinlbird]

Carb Issue

Took carb apart again. Somewhat better but still having trouble. Adjusted carb to run well, but after less than 10 minutes run time she starts getting same symptoms again. Wondering if I may have a leaking seal on crankshaft or jug gasket, crankcase gasket. It all seems to be affecting the low circuit of the carb any comments.

May want to check my thread "Husqvarna 55, Won't run (Fuel Issue)". They had some good answers that may relate to your issue too.

 

[lawnmowertech37]

I was wondering if any of you guys have swapped the WT 170 carb for something else or found a substitute for it. I have a 55 Husky just rebuilt the engine, new piston and ring, wrist pin bearing gaskets the like. Even rebuilt the carb but still have a dead spot in the lower to mid rpm range. Set the carb L at 1 1/4 out and the H at 1 1/4 out, but doesn't run very well. Opened up the L circuit maybe another 1/4 total runs but still not what I like. I am afraid to mess with the High circuit much I am guessing it should not be closed more than 1 full turn open. I am guessing the problem may lie with the fuel pump side of the carb. I replaced it but the carb kit I used was made the same but with a different type material. Any help here would be appreciated. :deadhorse:

a WT-170 carb new runs $ 39.99 when purchased thru me anywhere else not sure but they retail for $ 42.00 just letting you know

calvin

 

[dumbarky]

Ok I'm lost a out of ideas

I have check this 55 over and over. I've rebuilt the carb cleaned the fuel line and filter. It has 140 pounds cold compression. I adjusted the carb to run perfectly and it will operate great for 1/4 of the tank full then the trouble starts won't rev up acts like it's not getting fuel. Then it won't idle correctly. These saws have a surge port to the carb not a surge line. Would it be losing pressure and vacuum thru the bearing seals after warming up to a certain point causing these symptoms. What am I missing. I have rebuilt carbs before on stihls with great results but this thing is kicking my butt.

 

[Saw Dr.]

I would test with a known good carb before going any farther. You might want to think about replacing the fuel line. It could be collapsing inside. Also, you're chasing your tail without a pressure and vac test. It would take maybe 30 minutes to make block off plates for the intake and exhaust, and you have spent nearly that much time on this thread.

 

[dumbarky]

Ok so how much pressure and vacuum should it hold and for how long. I figure 5 -6 psi would be alot of pressure. And how do you do a vacuum test.

 

[outdoortype]

Check the tank vent

If it runs well for a while then starts acting up it could be a heat/expansion issue. After it runs and gets hot to start acting up, lay the saw on it's side and slowly open the fuel cap. If you hear a hissing sound, the tank vent is plugged. You may have already done this, so I apologize if I'm waisting your time.
Also, I have a Zama C1 carb on my 51(same as 55) and it's been great so far-knock on wood. Husky used both the walbro and zama brands on that saw so maybe one is better than the other? Hopefully Cliff will chime in and help you out.

 

[Thorcw]

All of the 55 ive worked on with that problem have a bad fuel line around the grommet going into the tank pull it and check it. Its not a special line like a stihl so its maybe a dollar.

 

[dumbarky]

Ok so now I feel like a fool. The tank vent was stopped up. And surprise the fuel line has a little crack just inside tank. Cleaned the tank vent now its ok, but had to order the fuel line. Get back on it when part comes in.

 

[dumbarky]

Replaced the fuel line. I ran an entire tank thru saw yesterday without failure. Fired up today and still runs ok but the saw rev's up when you point the bar down. When you hold the saw level it idles down. So what up with that didn't do it yesterday but murphy's law strikes again.

Any thoughts will be greatly appreciated.