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Chainsaw Fuel System Problem

chainsaw fuel carb

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#1 HowardsMF155 ONLINE  

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Posted January 21, 2014 - 09:08 PM

I had the chainsaw out today taking down a dead tree for my neighbor next door.  While it initially ran well, it began to acted starved for fuel, but would restart after it died.  Opening and resealing the fuel cap didn't correct the issue.  It almost seemed that position was key at first, as it would run well for some cuts, then when held in a different position it would die again.  Finally, though it died and refused to restart.  At that point I noticed that the primer bulb would depress, but would not fill again.  I'm thinking clogged tank or fuel line, but would like some opinions.  Don't chainsaws have "floppy" pickups that tend to stay at the bottom of the tank?  Do chainsaws have fuel pumps?  Are the filters inside the tank and is there any good way to get to the tank.  It is a Homelite model, nothing special.

 

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Howard


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#2 Alc ONLINE  

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Posted January 21, 2014 - 09:16 PM

Don't those primer type systems pressurize the fuel tank with the primer bulbs ? Not sure ,,  I did have the fuel  line break in the tank and if it wasn't full it would stop running ,  and yes it had a filter on the end


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#3 Bmerf OFFLINE  

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Posted January 21, 2014 - 09:17 PM

Chain saws usually have a stone filter in the tank. The problem is probably the gas line has cracked. Use a piece of wire to fish out the line and filter. Replace all the gas line with new. Buy the good line. A little more expensive, but worth it. Good luck


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#4 trowel OFFLINE  

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Posted January 21, 2014 - 09:18 PM

Yeh, funny little 2-smokes,

There is a inline fuel filter in the tank, drain the tank and fish out the end of the fuel line and pull off the filter check the line to the carb for plugs, put a little gas in it and try it, if no go it could be the diaphragm in the car is dirty or needs replacing, before going that deep pull the air filter and try running, check the spark plug and pull the cover off the muffler and clean the screen. If no, then the carb.


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#5 Bmerf OFFLINE  

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Posted January 21, 2014 - 09:18 PM

Check the primer bulb also. Sometimes they crack with age.


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#6 Guest_Fluid_*

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Posted January 21, 2014 - 09:46 PM

What brand is it?  Sounds like the filter at the end of the fuel line in the tank like the others said.  Stihl has a summer and winter little plastic flap under the air filter cover. If its on the summer mod it will freeze gas when running in the cold, that will stop gas from flowing to the carb.Maybe you could check yours to see if yours has that option?  If all checks out OK, your carb is probably gummed up and needs cleaning.   Hope you can get it running soon.  Good Luck


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#7 Gabriel OFFLINE  

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Posted February 05, 2014 - 10:09 PM

Sounds like it could be the fuel line.


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#8 Guest_Fluid_*

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Posted February 06, 2014 - 04:23 AM

I had the chainsaw out today taking down a dead tree for my neighbor next door.  While it initially ran well, it began to acted starved for fuel, but would restart after it died.  Opening and resealing the fuel cap didn't correct the issue.  It almost seemed that position was key at first, as it would run well for some cuts, then when held in a different position it would die again.  Finally, though it died and refused to restart.  At that point I noticed that the primer bulb would depress, but would not fill again.  I'm thinking clogged tank or fuel line, but would like some opinions.  Don't chainsaws have "floppy" pickups that tend to stay at the bottom of the tank?  Do chainsaws have fuel pumps?  Are the filters inside the tank and is there any good way to get to the tank.  It is a Homelite model, nothing special.

 

Thanks,

Howard

HowardMF155 ; What ever happened with your chainsaw that wouldn't stay running? Were you able to fix the problem? If you did, what was it?   Just wondering.


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#9 HowardsMF155 OFFLINE  

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Posted February 06, 2014 - 08:30 AM

HowardMF155 ; What ever happened with your chainsaw that wouldn't stay running? Were you able to fix the problem? If you did, what was it?   Just wondering.

Hi fluid, Thanks for asking.  It turned bitter cold (for this area) the day after I posted this question, then snow, and some other issues like needing a new microwave, heat pump freezing up, etc., so the chainsaw is on the back burner.  The tree is down to three 6 ft stumps, so finishing that isn't a big push either.  When I get back on it, I'll post an update.


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#10 olcowhand OFFLINE  

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Posted February 06, 2014 - 03:28 PM

Yep, fuel line has fallen in-two inside the tank.  These fuel lines just don't hold up with this "modern" fuel.  Turns the hoses to mush.


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#11 HDWildBill ONLINE  

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Posted February 06, 2014 - 04:47 PM

Bmerf and OLC is right, your fuel line inside the tank has broken so that is why you get fuel at one angle and then turn it and it dies.  Get some new fuel line.  Drain your tank and clean out all the old fuel line. Pull the remaining fuel line out and off the carburetor inlet.   Might as well replace the fuel filter while you are at it. Take the fuel line with you so you get the correct size.  Next cut the end of the fuel line at about a 45* so you have kind of a pointed end.  Now take some wire like Theromstat wire and fun it down into the fuel tank and out the inlet.  take the wire and pierce the end that you cut so the point is kind of laying on the wire.  Now put the fuel filter on the fuel line at the other end.  Then put the wire back through and through the tank hole.  Pull it until the filter is sitting on the bottom of the tank and has some slack to move around.  Measure to the carburetor inlet and cut the fuel line and install it.  You should also do the vent line as well and you do it the same way you did the fuel line except you pull it all the way up to the top of the tank with just a little left in the tank maybe 1/4" but no more then a 1/2".  Also both fuel lines may be a different size so before you buy you fuel line check.  Good luck.


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#12 HowardsMF155 ONLINE  

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Posted May 19, 2014 - 08:12 PM

I finally pulled into this nightmare today.  I suppose it didn't help that I've never had one apart, because I kept looking for a way to get to the fuel tank, only to finally realize the tank was built into the frame of the chainsaw.

 

First issue, as suggested repeatedly here, was the fuel line fell apart.  Thank you government enforced ethanol.  However, apparently I got the "special" unit with a few other problems.  I notice the carb was moving independently of the engine, so I pulled that all the way off and found out that one of the mounting flange bolts had been over tightened and wrung off.  Also, the screw holding the choke plate on was ready to fall off.

 

So, I tightened the screw, tried and failed to get an easy-out into the broken bolt, drilled and tapped a hole anyway, put loctite on all the screws and reassembled the carb.  I also replaced the fuel lines, then put most of the chainsaw back together.  I tried to start it, but still the little bulb doesn't seem to be filling up with fuel.  I tried starting it, and after a few pulls the motor locked up, presumably a hydraulic lock from flooding fuel.

 

I refrained from chucking it onto the nearby highway.  I'm done for the night.  I may look at it tomorrow, or I may not.  

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#13 HDWildBill OFFLINE  

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Posted May 19, 2014 - 08:42 PM

Chain saws can be a real pain that's for sure.  Did you put some Loctite on that screw for the choke plate?  If not you need to go back and do that. If the primer bulb is not filling up with fuel then you may have the fuel lines on backwards. A very common mistatke.  If it still does not fill up with fuel then either you have a hole in the primer bulb or the carb diaphragm may have a hole in it. If the carb is the culprit then I would just replace it and save your self some aggravation. 


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#14 HowardsMF155 ONLINE  

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Posted May 20, 2014 - 03:22 PM

Bill, the fuel lines were of two types of material and it was only the intake which was visibly deteriorated.  So, I only replace the one, so it shouldn't be a crossed line issue.  

 

I did pull back into this saw today and found that some metal filings from yesterday had gotten caught between the flywheel and the ignition coil, so I cleaned them off and put everything back together with loctite as needed.  I cranked the saw and made two cuts in my neighbors yard, reducing her unwanted tree from a 12 ft stump to a 3 ft stump, then the saw started acting fuel-starved again, and dying when I turned it on edge to cut.  I may try to get a free carb from the maker, but otherwise I may just give up on this one and try another, though I can't say I'm optimistic about that.  This saw may be about 5-8 years old, and probably has less than 20 hours of operation on it.  



#15 Alc OFFLINE  

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Posted May 20, 2014 - 08:34 PM

Here's some good reading

http://www.justanswe...hen-turned.html


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