Can't start my hardlly ever used chainsaw
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A ten year old MCCULLOCH......the machine will need new fuel pipes from tank to the carb and back again as they deteriorate big time.
Does it have a primer bulb - it should be full of fuel if it has.
John
Does it have a primer bulb - it should be full of fuel if it has.
John
It's petrol conny, model Mcculloch MAC 7--40.
Burnerman, it has a primer bulb but difficult to say for sure whether it has petrol in it as the bulb is yellow like petrol. But it does make a squishy noise when pressed. One thing, when filling the tank I noticed a device in it with a plastic tail which had snapped from the inside of the cap.
Burnerman, it has a primer bulb but difficult to say for sure whether it has petrol in it as the bulb is yellow like petrol. But it does make a squishy noise when pressed. One thing, when filling the tank I noticed a device in it with a plastic tail which had snapped from the inside of the cap.
That device just prevents the cap from becoming lost - nothing to worry about here!
When you press the primer bulb, fuel should be pumped from the tank, up to the carb via a long pipe with a filter on, and then returned - by the shorter length of pipe this time to the tank.
Can you check to see it is doing this?
John
When you press the primer bulb, fuel should be pumped from the tank, up to the carb via a long pipe with a filter on, and then returned - by the shorter length of pipe this time to the tank.
Can you check to see it is doing this?
John
Take the spark plug out, look at it and see if it is wet with fuel. If it is, then it might help to dry it/warm it. I pop them on a gas flame, either gas torch, or gas hob, just long enough to burn off the fuel and warm the plug a little. Also check the gap, usually 25 thou..
John, found the long pipe which led to the underside of the carb which is inaccessible. Taking off the filter I assumed that squeezing the bulb would show petrol in the choke hole or at least a petrol smell. No luck I'm afraid. By the way there is petrol in the bulb.
I'm wondering whether petrol was left in the carb 10 years ago which has solidified.
Harry, not sure whether petrol would show on the plug during this but it was dry.
I'm wondering whether petrol was left in the carb 10 years ago which has solidified.
Harry, not sure whether petrol would show on the plug during this but it was dry.
You can try some raw fuel down the carb to see if the engine pops, but did you check that the fuel was actually circulating, as suggested?
There is a huge chance that stale fuel has interfered with the carburettor and personally I would change it for a non genuine replacement, usually around the £15 mark from Amazon. Normally McCulloch use a Walbro type carb but there will be identification marks on yours.
The fuel lines are likely to be hard and perished and often a replacement carb comes with those too.
John
There is a huge chance that stale fuel has interfered with the carburettor and personally I would change it for a non genuine replacement, usually around the £15 mark from Amazon. Normally McCulloch use a Walbro type carb but there will be identification marks on yours.
The fuel lines are likely to be hard and perished and often a replacement carb comes with those too.
John
Here is update on getting my Mcculloch to start. I found a local expert on chainsaws. He thought I might need a new carb. Anyhow it just needed a new diaphragm. He gave it a thorough overhaul and it now starts okay. £35.
The handbook says 1 part of 2-stroke oil to 40 parts of petrol. But that was before E10 petrol. Some sites say 1 to 50. Would welcome any views?
The handbook says 1 part of 2-stroke oil to 40 parts of petrol. But that was before E10 petrol. Some sites say 1 to 50. Would welcome any views?
That’s an amazing repair price! Often the diaphragms are more expensive than a replacement carb.
Anyway, you can use ready mixed Aspen fuel or a 50:1 mix of Oregon oil, or maybe a small bottle of Stihl or Husqvarna oil that you mix with 5 litres of fuel.
I’d recommend the Aspen fuel in your case although it’s more expensive.....E10 petrol makes no difference although it does seem to go off quicker.
John
Anyway, you can use ready mixed Aspen fuel or a 50:1 mix of Oregon oil, or maybe a small bottle of Stihl or Husqvarna oil that you mix with 5 litres of fuel.
I’d recommend the Aspen fuel in your case although it’s more expensive.....E10 petrol makes no difference although it does seem to go off quicker.
John