Husqvarna 51 won't stay running

[hungrybare]

Hey guys, I am in need of a little advice from the experts. I have a Husqvarna model 51 I got from a friend who gave up on it. It starts, runs for a little while and will rev up once or twice then stall. seems to be running out of gas. it has 150 psi compression, new plug, carb, gas lines and fuel filter. Just for kicks I took the carb apart and checked everything, but didn't see anything abnormal, I think it is the same problem as with the old carb. I checked the bottom end with a vacuum gauge. piece of rubber to block the exhaust and intake, etc. I pumped it to 10 inches of vacuum and it does leak down to less than 5 in about 20-25 seconds. Would that be enough to cause the problem? Any help would be greatly appreciated !!!!! Thanx !!!!!

 

[eriklane]

did you check the base gasket? I recently had one blow out without my knowledge, however, the messy oil all over should have clued me in quicker...also make sure your air cleaner is clean. I recently came to realize that rapping them on the bench isn't clean....spray them with brake cleaner and air...now it starts in 3 pulls, used to take 6...simple. Also, for less than 10 bucks, rebuild the carb. I once found a bunch of wood crud in my big saw carb screen, and these things go bad eventually, so just do it. It takes just a few minutes.

 

[Busmech]

Check the fuel line between the airbox and the fuel tank, I have found problems with the line there on more than one 51/55 saw

 

[hungrybare]

Check the fuel line between the airbox and the fuel tank, I have found problems with the line there on more than one 51/55 saw

Thanx for the suggestions guys, The carb is new, not a spec of dirt in it. Base Gaskets look good. There is only one hose in the gas tank with the fuel filter which goes to the carb. Just don't see a vent hose anyplace. I must be missing something, just wondering if the slight drop in vacuum when testing the bottom end could be a problem or not?

 

[HiOctane]

Its hard on those saws to get a good reading due to their rubber flange intake.Did you check with some liquid if you see some bubbles coming out from seals,base gasket,etc ? Be sure the small intake rubber grommet is not damaged.

 

[a. palmer jr.]

I just looked on the IPL and didn't see any tank vent but I'm sure it has one. Might be built into the side or top of the tank that can't be seen on IPL. If you think it might be the vent just run it with the gas cap loose for a little while with the cap facing up to test it.

 

[HiOctane]

I just looked on the IPL and didn't see any tank vent but I'm sure it has one. Might be built into the side or top of the tank that can't be seen on IPL. If you think it might be the vent just run it with the gas cap loose for a little while with the cap facing up to test it.

Its on the side.

 

[hungrybare]

With the vacuum gage I have it is not capable of pressure so I need to get one that I can pump pressure in the bottom end and check for bubbles around the seals and base gaskets. really don't want to use the air compressor. I kinda want to check everything over close again before I put it back together, Thanx !!!!

 

[Gypo Logger]

If the 51 is anything like the 50, the fuel line can get pinched between airbox and casing.

 

[zogger]

Air leak someplace. Try a small amount of pressure, and squirt soapy water around base gasket, seals, intake at cylinder, etc., to find the leak. If it isn't in the fuel line itself.

 

[hungrybare]

Hey, guys, I just couldn't wait for a pressure pump so I put the 51 back together and found the plastic threads that hold the carb to the manifold were stripped on one screw. So being impatient and not wanting to wait for a new one I filled the hole with epoxy, drilled and tapped new threads. I filled with gas and lo and behold there was a crack in the fuel line cause the rubber grommet was worn where it goes into the tank and fuel line was rubbing on metal. Needless to say it runs good now. I guess sometimes I have a hard time following my own advise and check the simple stuff first. Thanx for all the response and advise guys (Logger, you were spot on) Thanx again !!!!!

 

[grizz55chev]

Epoxy isn't strong enough to hold for long, insert a piece of zip tie along side the screw when you install the carb. The screw will make new threads and hold strong.

 

[grizz55chev]

I use an old bike pump with the guage built in to pressure test, about 7to 10 lbs, spray soapy water around suspect areas look for bubbles. I've found leaks everywhere you could think from impulse lines to spark plugs and base gaskets.