Chainsaw Repair
Husqvarna - Stihl - Poulan - Jonsered - Dolmar chainsaws and more => Husqvarna => Topic started by: jrbarba on April 21, 2014, 08:49:11 am
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I’m back about the Husky Special 50. I cannot get the saw to start. I know I have spark because when I use starting fluid, it will turn over. It runs til it burns the fluid then quits. I have replaced fuel filter, fuel line, and did a partial rebuild on the carb, replacing the pump diaphragm, metering diaphragm and gaskets. The screen was clean. When I finished, the saw wouldn’t start, but I realized I might have the L and H out of adjustment. When I turned them both out, the saw started and ran while the control was locked, but when I released the lock, the saw died. I suspected it might be throttle related, but I don’t see that adjustment will change anything. Now, it will start with starter fluid, but quits after the fluid is burned. This still sounds fuel related, where do I go next?
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Tune the low needle for best running with the throttle locked.
Before unlocking the throttle screw "in" the idle speed adjustment.
Unlock the throttle and try again for best running at idle.
Keep working at it until you get the saw speed down low enough that the chain doesn't spin.
Now you must get the engine where it will accelerate which will involve screwing out the low speed needle to where the engine will take the throttle.
Start with the needles at two turns . . .
We can talk about the high speed screw after you get the chainsaw to idle and accelerate?
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Tune the low needle for best running with the throttle locked.
Before unlocking the throttle screw "in" the idle speed adjustment.
Unlock the throttle and try again for best running at idle.
Keep working at it until you get the saw speed down low enough that the chain doesn't spin.
Now you must get the engine where it will accelerate which will involve screwing out the low speed needle to where the engine will take the throttle.
Start with the needles at two turns . . .
We can talk about the high speed screw after you get the chainsaw to idle and accelerate?
That's the problem, the saw won't run long enough (when starter fluid burns, it stops dead) to adjust anything.
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That's the issue. When the starter fluid burns the saw dies, so it isn't on long enough to adjust anything.
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1) Don't use starting fluid in a two stroke engine
1a) Make sure that you have no kinks or sharp bends in the new fuel line
2) Get yourself a squirt bottle that you can use to squirt a little pre mix in the carb
3) Set the H&L jets at 1 turn out from lightly seated
4) Start pulling with the saw choked
5) When the saw fires return the choke to the run position but do not pull the trigger because the throttle is automatically set to fast idle by previous setting the choke to on
6) Pull again a couple of times, saw should start or at least fire a couple of times
Plus what 660 said above!
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I hear you about the starting fluid. There is no manual choke. When the trigger is locked, it holds the choke open; when it is released, the choke closes. I did start out with 1 turn on the screw, but it would not start. I checked the fuel line, there are no kinks or sharp bends. I will try this later today and post my results. Thanks for the direction.
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How can I post pictures? When I try, it says they are too big. Is there a special location?
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There are usually three adjustments to the carburetor. 'T' = throttle, 'L' = low speed and 'H' = high speed. H&L set to 2 turns out (per 660, lets stick with one set of instructions) from lightly seated. As 660 said,
Tune the low needle for best running with the throttle locked.
Before unlocking the throttle screw "in" the idle speed adjustment.
Unlock the throttle and try again for best running at idle.
Keep working at it until you get the saw speed down low enough that the chain doesn't spin.
Now you must get the engine where it will accelerate which will involve screwing out the low speed needle to where the engine will take the throttle.
Start with the needles at two turns . . .
We can talk about the high speed screw after you get the chainsaw to idle and accelerate?
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stop using starter fluid. worst thing to use period.
get a small squirt bottle and put some properly mixed fuel in it.
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Okay Killian, gas in carb, starts on 3rd pull, runs for a few seconds, cuts out. This is with 2 turns out on L. Handle locked so choke is open.
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How can I post pictures? When I try, it says they are too big. Is there a special location?
To use software here you need to resize before uploading Restrictions: 8 per post, maximum total size 6400KB, maximum individual size 405KB
or use a free host like photobucket and it will resize for you when you upload pics to them. Then just copy and past IMG code here.
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Sounds like it is not pulling fuel. Are you sure you have the diaphragms and gaskets in the carb in the right order? If backwards the carb will not pull fuel. They go in different order depending on which side of the carb you are working on.
Have a look here:
http://chainsawrepair.createaforum.com/ported-saws/walbro-carb-info/ (http://chainsawrepair.createaforum.com/ported-saws/walbro-carb-info/)
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I used a you tube video https://www.youtube.com/watch?v=FRfKPhmAJ9o. Followed it step by step; but I can always be wrong. I will use the links you sent to double check my work. That's what I was thinking, except it did start and run. When it did, I let it run for about 5 minutes before I released the throttle, and then it died. It restarted right away (three more times), but each time when the handle was released, it stopped. That lead me to think it was choking out, or the mixtures were off. When I went to it a couple of days later (today), it was back to not starting again.
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Howdy,
When you disconnect the line at the carb, do you have fuel?
As far as starting goes, 50's have a funky choke system. It has a slide in the top cover that uses a piece of spring steel to partially collapse the air filter thereby covering the intake opening, and causing the choke. Take the top cover, and air filter off. Place your thumb over the intake opening when you crank the saw. If it primes and starts, you have a choke issue.
Regards
Gregg
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KilliansRed,
Checked carb assembly - all good. I am baffled. Rechecked the screws, all good. Put fuel in carb, she starts after w or 3 pulls; then just craps right out. Other than doing a total rebuild or buying a new carb, I am out of ideas. What do you think?
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Did you try what Grande Dog suggested in the previous post? What he is suggesting is systematically eliminate each part of the fuel delivery system starting with the fuel supply. Disconnect the line from the carb and turn the saw onto the clutch side to see if fuel flows. If fuel can flow from the tank when not connected to the carb you know that the pick up hose is not kinked. If fuel does not flow then it is either a kink in the line or the tank vent is blocked. If when you try this fuel does not freely flow out the line, then open the tank cap, if fuel flows then it is most likely that the vent is clogged.
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Yep, fuel flow is steady with cap on. Also, I did cover the port with my thumb when I had it briefly running and it choked it right out. Tried with the cover on and filter mashed; tried it with the cover and filter off. Result is always the same.
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OK, so now we know that the problem is beyond the tank and fuel delivery from the tank to the carburetor. We will leave the carb internals alone for now since you just put a diaphragm kit in it. The carburetor is essentially a pump, it uses pressure from the spinning engine to pump fuel from the tank and delivers it to the engine.
There is what is called a pulse tube that connects the engine to the carburetor, in the case of the 50 Special this tube is built into the heat shield (501 77 11-01) it is the rather pointed tube that protrudes from the cylinder side of the heat shield. (See attached picture). There are two rubber parts that connect the heat shield to the cylinder that are notorious for failing. They are ( 503 16 16-02 induction pipe) and ( 503 31 07-51 pulse grommet), there is also a carburetor gasket (501 77 00-02). The pulse grommet for the 50 Special is NLA however I believe that the grommet from a 50 Rancher will also work (505 31 07-51).
If the grommet is bad (or missing!) between the cylinder and the heat shield you will not get enough 'pulse' to draw fuel. Like wise if the gasket between the heat shield is not aligned properly with the carb side of the heat shield the pulse will not get to the carb and pull fuel. If you look closely at the engine side of the carb you will see a small hole in the front face of the carb (pulse inlet) this must not be blocked, the gasket also has a small hole that must be situated such that it does not block off the pulse inlet to the carb otherwise no fuel!
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So, by now you should know where this is going. If there are no problems with the tank and its' fuel lines or vent and there are no problems with the pulse getting from the engine to the carb: then the only thing left is the carburetor itself.
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Hi, brand new member here-
Does anybody know if the OP solved his problem? I have exactly the same saw and problem; changed the carb, fuel line, filter etc; saw starts, runs 5-10 seconds and then dies out of fuel. It will start up again in a few minutes with the same results. Once it ran and cut for 15 mins, thought it was good and shut it off, problem returned. Sounds like I should go to the pulse tube next?
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I had a chainsaw with a external pulse tube do this and the tube was loose at the carb. The impulse tube would make enough contact with the carburetor to start the saw but vibration would hold it off the carburetor (randomly) and make the chainsaw act as though it ran out of gas.
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I didn't notice anyone mention the metering lever. If not set correctly (flush with body of carb) it won't pump enough or will pump too much fuel.