Husqvarna 55 Rancher bogs down in cut

[Megunticook]

2004 Husqvarna 55 Rancher, big loss of power in cut, RPMs drop. Chain sharp, tension adjusted. Fresh fuel. No smoke.

Figured I had the carb. mixture mis-adjusted, I riched out the H screw a little at a time to about 2 turns out from seated. I removed mixture screw limiters a couple carb. rebuilds ago. Tach. wasn't reading properly so had to tune as best I could by ear. When I first tuned it in December it was smoking a tiny little bit, but without the tach. I figured better a little too rich than too lean. Power seemed fine. I've run 5-6 tankfulls through it and just noticing the power drop now.

Brought saw to bench and pulled carb., disassembled, placed in ultrasonic cleaner. Pulled muffler and checked piston (replacement OEM cylinder/housing assembly I installed last spring, have run maybe 1-1/2 gallons through it since then). Piston looked like new.

Spark plug was mostly light gray but slightly dark on one side, but not all sooted up. Was installed new last year.

No carbon on muffler screen.

Intake manifold seemed snug and well fitted. I replaced that last spring.

What am I looking at here? Should I change fuel filter? Fuel line? What else could be causing this power loss?

I dropped a dead red oak today, maybe 16" diameter, got it about half bucked and I just couldn't cut through it anymore, the saw lost so much power. Frustrating!

 

[Saw Fixr]

Did you check the rubber impulse tube? The intake bulkhead, while mounting to the saw crankcase, has to also fit tightly into the impulse tube. If the tube is damaged or worn it could give problems like this.

 

[Saw Fixr]

Forgot to add....also check the intake where the carb screws into the plastic intake. Those threaded holes in the plastic can strip easily and cause an air leak

 

[Megunticook]

I replaced the rubber impulse piece as well as the intake manifold last year due to an apparent air leak and pretty sure those are still good, but I could be wrong.

Reassembled everything after cleaning/inspection, also replaced fuel line and filter. New plug.

Could barely get it to start. If I got it to fire up briefly it stumbled and died if I squeezed the accelerator. A little smoke at one point, not too much. Both needles were out 1 turn from seated.

I didn't have a spare carb. kit when I reassembled that carb., so I just used the old parts (which are maybe a couple years old). I've ordered a rebuild kit and will try rebuilding the carb again.

This saw was flawless for 14 years with just basic routine maintenance but the past couple years have been a headache. Wish I could get it back where it was, such a reliable workhorse when it's running right. I'm tempted to just buy a new carb. (had to do that once before after an attempted rebuild on the original).

Don't laugh, but I ordered one of Husky's battery powered saws. I know it won't have the same power or bar length but from what I'm hearing it will handle 75% of what I do (felling small to medium sized hardwood trees and bucking firewood length). I respect the Rancher, don't get me wrong, but I've always hated working around little 2-stroke motors. Maybe I can just save the Rancher for when I really need it.

 

[Saw Fixr]

Well, a new aftermarket carb will be cheap and you could at least use it for troubleshooting...

I worked on a Husky 51 today (that I resurrected for a friend a year ago ) with similar issues, almost like the choke was on.... turned out it was the muffler screen. I know you said yours is clean...

 

[Megunticook]

My last rebuild failed so I bought a new carb. Maybe it's time to do that again...although this time I used a new ultrasonic cleaner I picked up about a year ago. Was hoping that would make a difference. When the rebuild kit arrives I'll give it another shot but if that fails I should probably just get a new carb assembly.

Are the aftermarket ones OK or better to stick with genuine Zama?

Funny, I've got a Zama carb on my 4-stroke outboard that I rebuild every year and it runs fine. But haven't had the same success with the saw.

 

[cuinrearview]

How's it run with the air filter removed?

 

[Megunticook]

Haven't tried removing the filter...isn't that a big no-no? Were you thinking to test if the mixture was way too rich? I would think it would have smoked a bunch if that was the case.

Anyway I already pulled the carb., disassembled, and gave it another round in the ultrasonic cleaner. As soon as the rebuild kit arrives I'll take another crack at it.

But this is the second time I've tried and failed to rebuild the carb. on this thing. But have done it many times on my 4-stroke and an old Chrysler 318 motor I used to have.

If I do end up replacing the carb., where's a good source? I usually shop at Bailey's but they want $75 for a new one.

 

[sunfish]

With all you have replaced, it sounds like a carb problem. Is your chain getting plenty of oil? No chain oil will kill power in the cut.

 

[Megunticook]

Chain seems well oiled.

Should I remove the welch plug in the carb. and put the body in the ultrasonic cleaner again? Do you just drill a little hole in it then stick something in there and pry it out? I notice the rebuild kits come with a replacement. Maybe there's a problem somewhere under there.

 

[sunfish]

Chain seems well oiled.

Should I remove the welch plug in the carb. and put the body in the ultrasonic cleaner again? Do you just drill a little hole in it then stick something in there and pry it out? I notice the rebuild kits come with a replacement. Maybe there's a problem somewhere under there.

I'm not sure about your carb. If a kit won't fix em, I get a new one. All but two of my saws take the same carb, so I check eBay occasionally & buy the best deal.

 

[dsell]

There are many things that could be wrong. Remember, you can't always trust new parts. You need to perform tests to eliminate some of these.

1. bad sparkplug, they can fire out of the cylinder, but maybe not under pressure
2. bad coil, I've lost power from a coil going bad and I don't use the Chinese coils.
3. coil wire arcing against case
4. loose flywheel, key broke, out of time
5. air leaks, plastic intake is usually warped where it mates to the carb, impulse tube, intake tube, and crank seals
6. bad kill switch or wire bare
7. plugged tank vent
8. kinked fuel hose
9. bad fuel filter, I had a new fuel filter that cost me 8 hours worth of troubleshooting. It was aftermarket and the chinese left a disc of plastic in it that acted like a check valve.
10. plugged spark arrestor, which you checked.
11. scored cylinder
12. low compression due to too little squish on aftermarket parts, I realize you used OEM.
13. plugged filter in the carb
14. dirt in the carb
15. gaskets leaking in the carb
16. inlet needle not holding pressure
17. gaskets in the wrong order, it's easy to do.
18. wrong meter plate gasket
19. wrong gaskets, diaphragms, spring, OEM is best.
20. meter lever set wrong


Try a sparkplug from a known good running engine.

Disconnect the fuel line from the carb. Connect a syringe to the fuel line and you should be able to easily draw fuel from the tank. This tests the fuel line, filter, and possibly the tank vent. The fuel will ruin the rubber in the syringe. You could use a brake bleed kit, but syringes are cheap and easy.

A good compression tester meant for small engines is a must. A Mityvac kit with a bunch of fittings that does pressure and vacuum is very helpful. Take the muffler off and make a cover for it with metal or wood and rubber cut from an inner tube. Then, get creative on blocking the holes. Either adapt your pressure fitting to the carburetor, intake, or sparkplug hole. If you adapt to the sparkplug hole, then put a piece of rubber between the carb and intake to block it off. Pump it up to 7 psi and use a spray bottle with soapy water and spray on all the joints that could leak. I've even dipped the saw in a 5 gallon bucket of water.

Take the carb off and hook 7psi to the fuel inlet. Dip the entire carb in water and see where the bubbles come out. If it's around the fuel pump cover, the gaskets are bad or the body has a problem. If they come from the venturi, the inlet needle and seat isn't holding.

If you don't have a mityvac, about 2 pushes on a primer bulb is 7 psi if you have one laying around.

Find an exploded view of your carb and make sure it's together correct. The little welch plugs can be tricky. There is a little chisel that can be used to punch the center. Usually, punching the center craters it and then it comes out before you get the chisel punched through. You have to be careful not to damage the edges the plug seals in. Then take a small wire and pass through the holes it exposes. I always try to leave them alone the first go around.

 

[vizette]

Second the spark plug, just to make sure... Sounds weird, but it happens. I had a chinese branded one I got with an aftermarket carb. Every saw I put it in ran like crap. Out of the saw, it sparks just fine, jumps a nice blue spark, but I finally ended up tossing it (not even sooted yet) because every time I used it, I ended up replacing it with a champion or ngk and it was a night and day difference.

Brings me to my second question... you say the plug is light grey? I always expect to see light brown (coffee with cream or caramel color). Is that color normal for you? Just wondering if it's the oil you're using that might make it grey instead of brown, or if it's a lean condition.

If you meter lever is set wrong, you might not be getting enough fuel even with the high needle out. Does it 4 stroke WOT no load and then clean up in the cut? If you can't get it to 4 stroke, you're most likely lean, and the more you run it the less it likes it (plus you risk severe damage). Obviously there are other sources that could lean it out, like a cracked carb boot, just throwing this out there as another option.

 

[Megunticook]

Thanks for the replies. I mentioned earlier that I put a new plug in, new fuel filter, new fuel line, cleaned the air filter. The top end is new, I replaced it with an OEM kit and it's only had maybe 8-10 tankfuls run through it since then.

Oil is same Husky brand I've always used, so I don't think that's it. There may be an air leak I suppose, but I checked everything pretty carefully when I replaced the top end, installed new impulse rubber, new intake manifold, etc. But I never did a compression test. My gut sense is this is fuel related but I could be wrong. Bailey's has not even shipped my carb. kit after a week, not sure what's going on, so I tried my local dealer (they say they can get it in next week). Also found a relatively cheap OEM carb. online so ordered that as a backup plan. Determined to get this thing back to its old rock-solid reliability.

Meanwhile the cordless Husky came the other day and I tried it out yesterday for the first time, bucking some red oak logs up 10 about 9-10" diameter. The tool feels light and flimsy but I have to admit it went through that oak just fine. And sure is a whole lot more pleasant to work with without the smell and noise. I may save the Rancher for the really heavy-duty tasks.

 

[dsell]

I had new parts too. Take a look at this:

https://www.arboristsite.com/community/posts/6472255/

 

[Patrick1903]

@Megunticook

Did you ever figure out the problem with your Rancher?

 

[singinwoodwackr]

Similar to an older 61 I rebuilt recent. Try opening up the Lo screw until you get fast trigger response. Mine wound up around 1 1/4 turns. Runs like new

 

[Megunticook]

@Megunticook

Did you ever figure out the problem with your Rancher?

I did--replaced the piston and cylinder, was a compression issue. I suppose after 16 years it was time. Running fantastic now. Still have the electric which I've come to respect and I actually use it more than the Rancher now.