Chain Saw Repair

[Dork Lard]

The best fuel pipe to use is called Tygon.....

I use Tygon 2375 tube for brake fluid & Codan 3133 for fuel on motorcycles.

They say that after the next ice age, when Time Team excavate the desert plains of the savanah in the year of our Lord 5023, they will come across a small length of Tygon 2375 & wonder what use primitive man had for it !

 

[Munroast]

The best fuel pipe to use is called Tygon.....yellow in colour and seems to be pretty indestructible so far.
I’ve been replacing these pipes for ages now, long before petrol was designated E5 or E10. - just unleaded had to do!
Deterioration is due to heat and light as well as fuel.
Be aware, there are many different diameters of tygon pipe, both internal and external so out with the vernier!
Best to use premixed aspen fuel or equivalent, £20 for 5 litres just now.
I’m pretty sure those pipes will just push in, but do clear the crap away first!
GHS Ltd can fix you up.
John

As suggested the pipe did just pull out. The only part of the pipe that had perished was the end that would lie in the fuel (so petrol on both the inside and outside)

Pipe is somewher between 3 & 3.5 mm in dia. Will just buy what ever is available locally.

No way I am paying 20 quid a gallon for that aspen stuff.

 

[Burnerman]

Aspen fuel is perfect for those who use around a litre of petrol per year - it can save loads of machine down time, particularly in two strokes.
Personal choice, of course!
Do check both internal and external diameters, Mr. M.
John

 

[jeds]

Did my Husky saw recently. Wife said it's god knows how many years old and to just buy a new one. (she doesn't understand) The pipe (push fit) came out ok but the part inside the tank just disintegrated. Replacement pipe with new filter and a good clean up and (drumroll) nothing worked. So, new carb kit, thorough clean and rebuild and (drumroll) nothing worked. I can start it with a spray of quick start but it then just stops. I contemplated setting fire to it but my wife reckons that won't help. She's now looking at me with that 'told you' sort of face.

 

[fourtytwo]

Did my Husky saw recently. Wife said it's god knows how many years old and to just buy a new one. (she doesn't understand) The pipe (push fit) came out ok but the part inside the tank just disintegrated. Replacement pipe with new filter and a good clean up and (drumroll) nothing worked. So, new carb kit, thorough clean and rebuild and (drumroll) nothing worked. I can start it with a spray of quick start but it then just stops. I contemplated setting fire to it but my wife reckons that won't help. She's now looking at me with that 'told you' sort of face.

I think I am right that this new fuel requires a richer mixture, certainly I have had to tweek a number of my small carbs to get them to run like they used too. The other thing is all sorts of other gubbins delights in failing as soon as you look at one part so worth taking the plug out scrubbing and re-gapping, check you have not upset the magneto (check you can see a spark) etc etc

 

[jeds]

It does spark. It actually starts with a squirt of quick start. But won't run on it's own. I'm short of time at the moment but will be giving it another go over the weekend.

 

[Burnerman]

Does the saw have good compression?
It's often a good move to pop the exhaust silencer off - there you can see the state of the piston rings and barrel.
John

 

[jeds]

Compression is fine. As I say, it runs well with a squirt of quick start. I think the problem is the fuel isn't pumping, or whatever it does because there doesn't seem to be a fuel pump? The fuel line runs directly from the tank to the carb, exactly as it did before.

 

[Roy Bloom]

No way I am paying 20 quid a gallon for that aspen stuff.

Aspen fuel is perfect for those who use around a litre of petrol per year - it can save loads of machine down time, particularly in two strokes.

I run the m/c dry then run it on a tiny bit of the proper stuff for a few minutes for storage.

 

[Burnerman]

Compression is fine. As I say, it runs well with a squirt of quick start. I think the problem is the fuel isn't pumping, or whatever it does because there doesn't seem to be a fuel pump? The fuel line runs directly from the tank to the carb, exactly as it did before.

The fuel pump is incorporated within the carburettor.......one of the diaphragms has two U shaped flaps that cover drillings in the carb body.
This is the pump diaphragm.
The other one with the metal disc in it is the metering one.
I'd recommend replacing both - or maybe sourcing a replacement pattern carburettor.
John

 

[jeds]

OK, thanks for that.

 

[Munroast]

Aspen fuel is perfect for those who use around a litre of petrol per year - it can save loads of machine down time, particularly in two strokes.
Personal choice, of course!
Do check both internal and external diameters, Mr. M.
John

How important would the internal dia be ?


Replaced the pipe today, but it ain't fixed it. Same problems as before. It will start, but as soon as I try to rev it, it dies. And if it doesn't die it runs poorly, and does that curious thing of sucks its own plunger in (the rubber thing you press to prime it)

The other thing that I find a little odd is; after I have been trying to run it, when I disconnect the feed pipe from the carb, it starts squirting (a gentle squirt) from the pipe, it is as if the fuel tank is under pressure and is forcing fuel through the pipe.


I'm guessing dirt has got into the carb after the filter come off the end of the feed pipe, but very confused with the tank seemingly under pressure?

 

[Burnerman]

If the internal diameter is too small, it may split where it pushes onto the carb nipples - too large and it leaks.
There's a carb issue here.......when you push the primer bulb, can you see fuel returning to the tank? In theory, you can't over prime due to this function.
For sure, the primer bulb mustn't be sucked flat!
You have the fuel pipes on the correct way round? If the tank is brimmed with fuel, the carb can draw from either pipe for a short while!
John