Husqvarna 455 rancher help needed

[bretts]

G'day
I have a Husqvarna 455 Rancher that I am having trouble with.
I start it on choke and it runs but revs really high, blip the throttle and it comes down to idling speed but dies when it idles.
Keep blipping the throttle and it runs but bogs and it will either die by itself while idling or will bog and die when I blip the throttle.
It generally will only start on choke.
I have pulled and cleaned the carb many times, have checked the diaphragms etc and they are sound.
Have swapped out the primer bulb= no change.
Have pulled the cylinder and resealed it, it has good compression.
I have done a vacuum/pressure test which confirmed no leaks.
Have tried many different spark plugs, many different fuel filters and checked fuel lines.
I am at a bit of a loss as to what it might be, my gut feeling is it's fuel related.
Any help appreciated.
Cheers.

 

[sledneck22]

(Silly question most likey) did you try to tune the carb? Probably with the special splined driver?

 

[bretts]

(Silly question most likey) did you try to tune the carb? Probably with the special splined driver?

Yes I did, no this one doesn't have the splined adjustment screws.

 

[Steve]

Has this passed a pressure/vacuum test?

 

[bretts]

Has this passed a pressure/vacuum test?

Yes it has. It also has good compression.

 

[Stump Shot]

G'day
I have a Husqvarna 455 Rancher that I am having trouble with.
I start it on choke and it runs but revs really high, blip the throttle and it comes down to idling speed but dies when it idles.
Keep blipping the throttle and it runs but bogs and it will either die by itself while idling or will bog and die when I blip the throttle.
It generally will only start on choke.
I have pulled and cleaned the carb many times, have checked the diaphragms etc and they are sound.
Have swapped out the primer bulb= no change.
Have pulled the cylinder and resealed it, it has good compression.
I have done a vacuum/pressure test which confirmed no leaks.
Have tried many different spark plugs, many different fuel filters and checked fuel lines.
I am at a bit of a loss as to what it might be, my gut feeling is it's fuel related.
Any help appreciated.
Cheers.

From what you say here, I would give the carburetor a pressure test at the fuel pickup location to .5 bar or 7 psi and see if it will hold. Check your fuel lines for holes or abrasions, especially where it goes through into the tank.
The diaphragms not only need to be sound but also very pliable/flexible.
Usually if over 2 years old a replacement diaphragm kit is in order.
Your problem sounds deeper than that and some times it's better/cheaper to replace the carb with OEM new.
At any rate I believe you're in the right area, good luck with your diagnosis.

 

[Husky268]

i work on a lot of 455's see a lot of bad fuel lines and that sounds like your problem.

 

[davidwyby]

Pressure and vac test lines and such.

@Stump Shot is the go to guy for trouble shooting from what I’ve scene around here.
Speaking of which, my newly built 266 bogger is waiting for me to diagnose at home…