Craftsman 2.3/16 chainsaw: won't run

[Rog]

Hey,

I borrowed this saw from a friend.

It ran fine for about 6 cuts.

It is not drawing fuel to the carb. It will run briefly when I pour gas down the carb. The fuel line is intact, and I blew it out. THe fuel passages in the carb appear to be open.

as anyone seen this sort of problem?

TIA,

Rog

 

[Rog]

Model #: 358-352350

 

[dougand3]

Multiple possibilities: fuel pump diaphragm stiff, gunk in carb screen, tiny carb passages gunked up. Probably needs ultrasonic cleaning when totally apart and a rebuild kit. Or find a carb that is similar and adapt it. IIRC, one time I used a MS170 carb on a Poulan Micro XXV or S25DA. Pay attn to carb throttle/choke links and where impulse hole is located. Those carbs are $6-$8 on ebay.

 

[Jon1270]

THe fuel passages in the carb appear to be open.

Can you clarify what you're basing this on? Have you already disassembled the carb?

 

[Rog]

Hi,

I had the carb out, and removed the cover on the fuel inlet side. It looked OK, and I blew out the passages on that side. (I think).

I am ordering a rebuild kit this AM.

Rog

 

[Jon1270]

Hi,

I had the carb out, and removed the cover on the fuel inlet side. It looked OK, and I blew out the passages on that side. (I think).

I am ordering a rebuild kit this AM.

Rog

A rebuild kit might help, but you generally shouldn't use compressed air on these carbs. The main hazard is that a non-replaceable check valve in the high speed circuit can be damaged by excessive pressures, and if you do that then it's new carb time. Blowing through from the pump side while the metering cover is still installed could also (speculating here) damage the metering diaphragm. Just get a can of spray carb cleaner with the skinny red wand and use that.

 

[Jon1270]

Also, as Doug mentioned, be sure to check out the impulse circuit. It will either be a small hose going from the carburetor to the engine, or a small passageway though the intake block between the carb and engine. The impulse circuit is the route by which, as the piston goes up and down, crankcase pressure changes are used to drive the fuel pump diaphragm.

 

[Rog]

You guys are Great!

I will test the reassembled carb tomorrow and report back.

Many thanks!

Rog

 

[Rog]

Guys,

Still scratching my head....

Carb is very clean internally. Both diaphragms are flexible and intact. I blew out the fuel line again. It seems to be fine, but I can't remove the line due to the funky assembly design, that hides the last screw behind the fan. THe impulse circuit appears to be clear and OK.

I am going to get some fuel line and jury rig a gravity (test) fuel feed, since the carb appears to be OK.

I can't get a rebuild kit for several days, and I am not sure that I need it.

Any ideas are greatly appreciated.

Rog

 

[dougand3]

Tygon line in a jug of fuel mix is a good test. Could be carb needle lever is too high or low. If too high, saw floods and plug wet. If too low, no fuel into intake. I'd get an MS170 carb and try it.

 

[Rog]

Hey,

Bought and installed the new MS170 carb. I had to swap in the previous throttle plate.

The saw starts with fuel squirted into the throttle.

Using a gravity fuel feed the fuel does not appear to be flowing when the saw runs.

CHecked the Craftsman User guide: set the mixture screws per the guide: Closed both screws, then opened one turn each. Set the idle up.

The impulse channel to the crank and carb are both open: (Wire probe)

Is it time to negotiate a sale price with the owner??

Thanks for all the help.

Rog

 

[NateB]

Have you tried taking the fuel filter out of the tank, and try it with an open fuel line?

 

[Rog]

Yeah, not using the saw fuel tank or line. Gravity fuel feed to the new carb.

 

[Lcback]

Check your fuel filter.
That same saw is my only saw. It was given to me because the guy couldn't keep it running.
I changed the carb out. Nothing. Noticed I could hear something rattling around in the tank. The fuel filter broke off the end of the fuel line. I replaced the fuel line, reattached the filter and it's been running like a champ.

Sent from my LG-D850 using Tapatalk

 

[NateB]

Yeah, not using the saw fuel tank or line. Gravity fuel feed to the new carb.

I saw you tried the gravity feed, but unless you have created this system before, and had it work, there maybe be issues with the gravity system that will need trouble shooting. I think eliminating any possible obstruction in fuel flow in the original system, and testing is better then an unproved secondary system. It is just a suggestion, since I don't know your technical skill set.

 

[Jon1270]

The impulse channel to the crank and carb are both open: (Wire probe)

The typical problem with the impulse circuit isn't that it gets clogged, it's that it develops an air leak.

 

[Rog]

Guys,

I cleaned the insulator block under the carb, and installed 2 new gaskets. Gravity fuel feed has about 12 inches of head. Impulse circuit from block to carb is clean and open.

Same condition: It will run when I squirt fuel down carb. Does not feed fuel from aux tank. (air bubble in line does not move)

These saws are about $80 on Denver craigslist. I think its time to punt......

Thanks again.

Rog

 

[dougand3]

I'm with Jon that impulse circuit has a leak interfering with fuel pump diaphragm vibrating - esp if you put a new carb on it.. But this is a puzzler...the impulse circuit is merely a hole in the handle/carb housing that is open to crankcase. Is the black plastic housing cracked?
Are you sure you're getting carb impulse hole on carb housing hole, gasket has a hole there and no leaks?
I just parted out a Poulan 1800 - similar but 36.5mm piston. See pics.
Maybe it's a REAL BIG crank seal leak to disrupt impulse pressure to carb. And if so, the saw will be trash soon.

 

[woodhog73]

If you can grab another one for $80 bucks then sure perhaps it's easier to do that. Seems like a lot of trouble but on the other hand I understand wanting to save money .

If there was a large crank seal leak as stated above I would think the lean condition would be severe enough that you would tell the moment you pulled the muffler and looked at the piston. If that's the case I would junk the saw. No way it's worth rebuilding when it's worth $80 bucks. In my opinion anyways