What's on your bench today?

[GardenKit]

Well, the 026 is still proving annoying. Carb fully cleaned and carb kit installed, new impulse line (without even swearing, is this where I went wrong?) and new fuel line.

 

All back together, H and L screws at 1 turn and it won't now run at all. It's fine if you pour a teaspoonful in through the air filter - starts and runs fine. It just won't run on the carb at all.

 

Suggestions?

 

Alec

Alec, its obviously a fuel supply issue. As Rich says, it could just be that the carb is incorrectly assembled and the metering diaphragm is not pulling down far enough to open the needle. The 'pop off' test may prove this. With the carb in place pressurise the carb via the inlet pipe from the tank,then pull the saw over with the choke closed. Each induction stroke should see the pressure guage drop.

 

If it does not, then revisit the carb assembly.

 

If its OK then the problem may lie with the impulse. Your hose should be OK as its new, but check the gasket twixt carb and base plate. If its the wrong gasket, or incorrectly assembled it may be blocking the impulse passage.

 

Not sure what Rich means about pressurising the tank though.

[Rich2484]

What I mean is if the saw has been pulled over and you remove the fuel line from carb does it squirt a load of fuel out!

[agg221]

Cheers Rich, ideas much appreciated and spot on in identifying the problem.

 

Well, if nothing else I have become pretty quick at this - since reading your post I've started from fully assembled saw, stripped the carb, established fuel pressure was fine but not getting through to the top end. Realised I hadn't set the height on the metering arm, set the height on the metering arm, put it all back together again, started it and established it's fine. I make that a shade under half an hour all in.

 

It can now go off and be pressure/vac tested and tach tuned - assuming all's good I finally have a happy saw again and can carry on cutting up the milling offcuts for firewood.

 

Alec

Edited March 2, 2013 by agg221

[agg221]

And thanks Barrie too - I was actually outside testing it when you posted.

 

What I mean is if the saw has been pulled over and you remove the fuel line from carb does it squirt a load of fuel out!

 

Oh yes. It didn't catch me out this time around though - I checked it by opening the tank and listening for the hiss, rather than firing petrol across the kitchen (again). I know I use Aspen, and it's very clean and everything, but my wife was doing the dinner and I thought the Aspen/gas ring combination may not be optimum in a thatched house.....

 

Alec

[GardenKit]

This pressure is created by the vaporisation of fuel being shaken up, or heated up in the sun or by a running saw. It does help to push petrol through but should not really be needed as the fuel pump should pull the fuel through. After all, the tank will vacuum if the breather is blocked and the fuel level drops. It allows atmospheric air pressure in, it is this 14.7 psi pressure which pushes fuel up the pickup hose to the carb fuel pump when the vacuum is created in the pump on the induction impulse.

 

I do however often give a troublesome saw a good shake to increase the tank pressure over atmospheric to get a carb 'primed' ( OK , they should not need priming, but it does help)

[fen01]

Hi,

 

Conny bashing today has taken its toll on my kit today - 2 pull cords to replace (nice and easy) and the oiler has packed up on my little MS180. I was going to replace the sprocket and needle bearings so though i may as well change th pump, i have flushed out the oil tank and outlet and it seemed to oil fot abit but block as again. I haven't changed a oil pump before, so here is the questions, is it pretty obvious once you get the sprocket off? And where is the best place to buy a replacement pump from.

 

Cheers in advance.

 

Mark

[Daniël Bos]

Hi,

 

Conny bashing today has taken its toll on my kit today - 2 pull cords to replace (nice and easy) and the oiler has packed up on my little MS180. I was going to replace the sprocket and needle bearings so though i may as well change th pump, i have flushed out the oil tank and outlet and it seemed to oil fot abit but block as again. I haven't changed a oil pump before, so here is the questions, is it pretty obvious once you get the sprocket off? And where is the best place to buy a replacement pump from.

 

Cheers in advance.

 

Mark

 

It's just underneath the handle assembly. If you look underneath the saw you'll see the pipe from the oil tank to the pump just under the part of the handle assembly that runs front to back under the saw.

 

Pull out the hose, sprocket side (starter side is the tank) then you can use a normal metric thread bolt (m6 if memory serves?), to screw into the pump and just pull it up and out.

 

Easy job, but note which way round it goes so that when you put a new one in its the right way around.

 

I have a spare slightly used one, pm me your address if you want it.

[fen01]

Cheers,

 

I'll strip it down and check it out. If it needs replacing i will let you know. I assume that you need to remove the handle to get access -either way sounds simples enough.

 

Mark

[Rich2484]

What he said....

 

I had to delete an entire post because I got beaten to it..

 

Edit. While I'm thinking about it it could be the worm drive on the crank under the clutch and drum, worn out on one side causing it to oil for a bit then come off the thread and causing it to stop. Or the worm arm is not sitting on the drum properly?

Edited March 2, 2013 by Rich2484

[fen01]

What he said....

 

I had to delete an entire post because I got beaten to it..

 

Edit. While I'm thinking about it it could be the worm drive on the crank under the clutch and drum, worn out on one side causing it to oil for a bit then come off the thread and causing it to stop. Or the worm arm is not sitting on the drum properly?

 

Rich,

 

Thanks, I'll check that as well, might as well do it properly the saw is old, but it's a good 'un. Nice and light, ideal for hedges and light ground work.