McCulloch Pro 10-10a Bogging Down and Idling Too Fast

[RoncaliVineyard]

Hello Arborists,
I have posted before and had great responses that helped me with some issues I had with my McCulloch Pro 10-10A. Anyways, I am having a different issue now. My saw was running well about 2 weeks ago. It reved up fine and cut great. Now when I run it, it bogs down if I hammer on it hard. Holding the throttle down will eventually allow the saw to die. Simultaneously, it wants to idle high. Something seems to be screwed up somewhere, possibly the carburetor. I thought I would ask someone here before I tear into it. I wonder if this could be related to the coil. I have heard that some of these saws can be converted to electronic ignition, but I am uncertain of the status of my coil.

Thanks.

Josh

 

[lawnmowertech37]

it bogs down if I hammer on it hard.

that sounds like a fuel related issue i dont think its ignition related bogging down means the fuel is probily being resisted and not getting enough fuel or vise versa check the diaphragm make sure it is not brittle or have a pin hole thru it also check the fuel filter and the fuel lines for crimping lets rule out the carburetor first before going to electrical components also check the compression rate

calvin

 

[Cameljoe73]

:agree2: :agree2: LEAN LEAN LEAN, most likely an air leak, fuel line or seals, or the cab is falling off the saw. If you keep running it, there won't be any compression left to check.

 

[RoncaliVineyard]

Diaphram?

I will check the fuel line tomorrow. I am not sure what diaphram are you referring to? Where might it be? Is it part of the carberator? I know this is an old saw, so there could be some really old parts and some might need to be replaced. I will not run it until I figure out what is going on. Thanks to everyone for the great responses.

 

[Cameljoe73]

diaphram is under the top of the carb, 4 screws . But I havn't had a 1010 in 15 years, so I might be lieing to ya.

 

[RoncaliVineyard]

Fuel Line

The fuel line looks ok. It appears to be in good shape. I replaced the filter but it is too late to be firing up that thing. So I will check it tomorrow. I pulled the spark plug and it looked nice and brown, yet I need to buy a new one to see if it is running at the right mixture. Also inside the cylinder looked ok as well. It may be the diaphram, according to one of the other people that posted. Is the diaphram the flat shiny piece that says Japan on it. Four screws? With a hole in the center? Just checking. Thanks.

 

[Cameljoe73]

yup, thats it. Should be clean,and no holes in it.

 

[RoncaliVineyard]

Diaphram

With regards to the diaphram, should I remove the 4 screws and examine the diaphram? Or can I tell by just looking at it externally? I love this saw, despite it's age. I really love the older items. It is hard to go back to plastic once you use something old.

 

[Cameljoe73]

yep, need to remove the 4 screws, if it sticks carefully free it with a razor blade, if its in good shape, you will want to re-use it I'm sure.

 

[RoncaliVineyard]

Diaphram

I removed the diaphram. There didn't seem to be anything wrong with it. I still haven't fired it up after the filter change and diaphram check. I am hoping that it works fine, but I still need to check it out.

 

[mattinky]

I've seen quite a few diaphrams that looked good but would'nt pump fuel...

 

[Cameljoe73]

Well, double check there is no holes/cracks in the fuel line. Fire it back up, and see how it runs. (I bet you did this all ready) I wouldn't think that your carbs gunked up from old gas if it ran good 2 weeks ago. I think the next step is having the saw preasure/Vac tested.

 

[lawnmowertech37]

another thing it could be is check the muffler for a clog a clogged up muffler would cause problems too if the muffler cannot be taken apart i will check and see if i have one and let you know but pull that muffler and check it for a clog as well as clean it out expecally the screen in it

thanks
calvin

 

[RoncaliVineyard]

Diaphram and Muffler

After installing the diaphram and filter the saw will not start. I pulled and pulled but nothing. There seems to be vapor coming out of the exhaust, so I think maybe I didn't put the diaphram in correctly. Maybe? Also, the diaphram felt really flimsy and weak. There was a slight ripple on the bottom of it. Could this be an indication that it is worn out and needs replacement? If I change the diaphram, should I just rebuilt the carburetor while I am at it. They sell kits on mymowerparts.com for $11 shipped. Is that a good deal.

The muffler seems to not be clogged because vapor and exhaust has always flowed very well from it.

Any suggestions would be very helpful. Thanks for all the help already everyone.

 

[Wood Doctor]

After installing the diaphram and filter the saw will not start. I pulled and pulled but nothing. There seems to be vapor coming out of the exhaust, so I think maybe I didn't put the diaphram in correctly. Maybe? Also, the diaphram felt really flimsy and weak. There was a slight ripple on the bottom of it. Could this be an indication that it is worn out and needs replacement? If I change the diaphram, should I just rebuilt the carburetor while I am at it. They sell kits on mymowerparts.com for $11 shipped. Is that a good deal.

The muffler seems to not be clogged because vapor and exhaust has always flowed very well from it.

Any suggestions would be very helpful. Thanks for all the help already everyone.

Before you do anything else, remove the spark plug. Pour a couple of teaspoons of mixed gas in the combustion chamber. Replace the spark plug.

See if she will burn that gas. If not, you have no spark. If it starts to burn that gas, it may start the gas flow through the carb again and run OK. If it dies shortly, then you know you are starved for gas and no gas is making it to the combustion chamber.

 

[RoncaliVineyard]

It seems to be getting fuel.

It appears to be receiving gasoline because the spark plug is fouled. This is strange because now I have gone from too little of fuel to too much fuel. If I tip the saw over fuel comes out the exhaust. I think I may have installed the diaphram incorrectly, now maybe the needle valve is stuck open. I have spark because I checked it with an automobile spark plug tester. I have gone from one extreme to the next.

 

[RoncaliVineyard]

Running Again!

Hello Everyone,
Thanks to everyone here I have got my saw running again. I installed the diaphram incorrectly, I didn't attach the diaphram to the needle valve assembly, so it didn't work at all. It just poured gas all over the place. I installed it correctly and it fired up after a bit. It doesn't seem to be bogging down either. So I am not sure if it was the filter or the diaphram. I will probably replace the diaphram soon though. Is it supposed to be so flimsy? Anyways, thanks everyone for helping me through this inconvenience. I did not blow up the saw either. What a great day!

 

[Wood Doctor]

Hello Everyone,
Thanks to everyone here I have got my saw running again. I installed the diaphram incorrectly, I didn't attach the diaphram to the needle valve assembly, so it didn't work and all. It just pour gas all over the place. I installed it correctly and it fired up after a bit. It doesn't seem to be bogging down either. So I am not sure if it was the filter or the diaphram. I will probably replace the diaphram soon though. Is it supposed to be so flimsy? Anyways, thanks everyone for helping me through this inconvenience. I did not blow up the saw either. What a great day!

And I started my 1977 Mac 610 today after I wrote you the best advice I could give you. Runs beautifully. If you are just a little patient with a McCulloch, it will treat you like a million bucks.

You're Stihl in luck when you got a McCulloch chainsaw. :greenchainsaw:

 

[lawnmowertech37]

After installing the diaphram and filter the saw will not start. I pulled and pulled but nothing. There seems to be vapor coming out of the exhaust, so I think maybe I didn't put the diaphram in correctly. Maybe? Also, the diaphram felt really flimsy and weak. There was a slight ripple on the bottom of it. Could this be an indication that it is worn out and needs replacement? If I change the diaphram, should I just rebuilt the carburetor while I am at it. They sell kits on mymowerparts.com for $11 shipped. Is that a good deal.

The muffler seems to not be clogged because vapor and exhaust has always flowed very well from it.

Any suggestions would be very helpful. Thanks for all the help already everyone.

mowerparts.com
those people are my competitor
the part # for your Repair kit for the carb on the Pro Mac 10-10 A if your Serial # begins with a 11 or a 12 the kit # is 83764


it sounds like the diaphragm if it is stiff or brittle it needs replacing
calvin

also if you ever need any air filters i have access to them