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MAC 3200 will not start

Oct 24, 2019#1

G

ggratecc

Hi guys,
I have a McCullough MAC 3200 with a
symptom: will not start

Here are some photos:

I have fresh gas in the tank, bulb priming seems to work fine, checked sparkplug it looks new;
removed the muffler, closed the choke.

Tried pulling the rope and there are no sounds of it starting.
Tried engine start fluid , that did not work.
Tried different choke settings.

I tried adjusting the throttle screw a bit, nothing.
TIA,
Greg

Oct 25, 2019#2

dougand3

Best to use fuel mix, not starting fluid, in 2 cycles. You wash the lube off cylinder & piston.
1. Pull plug, put tsp of fuel mix in hole, re-install plug/wire, pull rope 10-20x. If you don't get a pop and maybe a 2 sec run, then you have a compression or spark problem.
2. Pull plug and ground metal side on engine. Pull rope and look for spark. Even with good spark - it could be at the wrong time - As in, flywheel sheared key.
2. Hold pull handle and let saw drop. Lug..........Lug..........Lug is good compression. Lug..Lug..Lug is bad.

Oct 25, 2019#3

G

ggratecc

Dougand3,
Thanks very much for your excellent reply!
Performed step 1.: after 20 pulls , the engine started right up and ran for about 15 seconds, then stalled.

So, then I'm thinking fuel system problem...
I pumped the bulb about 4 times and then pulled a few times and it ran again for 12 seconds and stalled.

Then, I noticed when I pushed the bulb, the fuel started gushing out of the top of the carb choke!!
I studied the way the fuel hoses run, took photos and made a crude drawing, see photos:

I think I know what to do next, but i'd rather you guys tell me which hose goes where on this Zuma!
I hope that I am describing the carb front and back properly...I'm describing carb front as being the side where the idle adjustment screw is.
TIA,
Greg

Oct 25, 2019#4

dougand3

Long hose with filter goes directly to carb nipple that is closest to the fuel pump side (1 BIG screw plate). Been so long, can't remember which side.
Long tube of bulb goes to fuel tank. Short bulb tube goes to other carb nipple.

Oct 26, 2019#5

G

ggratecc

dougand3 said:
Long hose with filter goes directly to carb nipple that is closest to the fuel pump side (1 BIG screw plate). Been so long, can't remember which side.
Long tube of bulb goes to fuel tank. Short bulb tube goes to other carb nipple.

Hi,
As you described I was able to reroute the three fuel lines properly, prime bulb worked fine and drew fuel through carb and back into tank!
I got it to run smooth for a minute or so, then stalled.
I got it started a second time also, then stalled quicker.
Then what I tried to pump the bulb , NO fuel is moving in the lines at all!
So I rerouted the fuel lines to by pass the carb , pumped bulb again and fuel flow just fine back to the tank.
My conclusion is the carb is in a state that will not allow fuel to be sucked through it, clogged?

Here are photos of the zama:

Any ideas? should I buy a new Zama carb? All I know is that it is a 32cc McCullough - MAC 3200. Anyone have a link to a carb replacement?
Does anyone think I can clean the carb and retest it? Do you recommend a rebuild kit? I feel comfortable taking it apart and rebuilding.
TIA,
Greg

Oct 27, 2019#6

dougand3

Pull the carb and read the #s. Maybe C1U-M35? Old carb that will be be NLA. Search ebay for "Mac 3200 carburetor" , "Zama CIU rebuild kit". You can try a thorough cleaning and rebuild kit but not always successful. You can search ebay for similar carbs and compare to yours - linkages, impulse hole. May find a similar enough carb to work.

Oct 27, 2019#7

G

ggratecc

dougand3 said:
Pull the carb and read the #s. Maybe C1U-M35? Old carb that will be be NLA. Search ebay for "Mac 3200 carburetor" , "Zama CIU rebuild kit". You can try a thorough cleaning and rebuild kit but not always successful. You can search ebay for similar carbs and compare to yours - linkages, impulse hole. May find a similar enough carb to work.

Thanks again for your reply...
It is a C1Q - M36 I discovered! So far I have not been able to find one of these in-stock. I will look for a similar one as you say.

I might just do a rebuild as you say, depending on what I find on similar carbs.
Q: if I clean and rebuild, should I remove the H and L adjustment screws?

Greg

Oct 27, 2019#8

dougand3

yes, gotta remove H&L screws. Turn In/CW first (light stop at end). Note how many turns to stop. Eg: 1.5, 1.25, 2.0. This is "turns out figure".
Impulse hole is on cylinder side of carb. Can be at 12 o/c, 10 o/c, 2 o/c. Look at the intake adapter - there will be a matching hole there. A new carb needs hole in the same place as old carb. (Some carbs have a 90* nipple w/ tube on fuel pump plate - but that's another story)

Oct 28, 2019#9

G

ggratecc

dougand3 said:
yes, gotta remove H&L screws. Turn In/CW first (light stop at end). Note how many turns to stop. Eg: 1.5, 1.25, 2.0. This is "turns out figure".
Impulse hole is on cylinder side of carb. Can be at 12 o/c, 10 o/c, 2 o/c. Look at the intake adapter - there will be a matching hole there. A new carb needs hole in the same place as old carb. (Some carbs have a 90* nipple w/ tube on fuel pump plate - but that's another story)

OK, took out the h/l screws, took carb apart, see photos.
I'm concerned about two things before I put it back together.
1. See the photo of the pump side where I show there are 3 gaskets, doesn't seem right to me. Shouldn't there
just be one thick gasket and one thin gasket?

2. See photo of other side with spring, needle and lever. I found I could not press down on the lever at all, thus the needle was not pushed up by the spring.

I would enjoy a quick reply by anyone.
thanks,
Greg

Oct 28, 2019#10

G

ggratecc

All,
One more question... See photo

See the little loose piece that goes in the long oval hole...
it looks like a little spoon.. wondering which way you install this, is
it with the depressed/rounded part DOWn or UP?
TIA,
Greg

Oct 29, 2019#11

G

ggratecc

HI,
Current status: I removed the H/L limiter screws, then cleaned and reassembled carb using instructions from ZAMA, as far as gas pump side and nozzle side.
Put it back in the saw.
At first pumping the bulb did not work, so I pulled the rope a few times and then got fuel to flow with primer system.
Unfortunately, I can not get it to start at all now. Also, fuel is leaking out of the muffler when pulling rope.

stumped.
Greg

Oct 29, 2019#12

dougand3

You need to see needle move upward ~1mm when you push lever. Needle tip and seat are probably damaged or full of gunk/varnish. Need to remove screw, spring, lever and needle to see. Sounds like bad flooding. Spoon is welch plug. It must firmly attach all around the 3 holes. Rounded side up. Some use nail polish to secure seal but I'd rather have a new plug. 1st pic has 2 fuel pumps - just need 1. Fuel pump against carb, gasket against plate.

You must get a rb kit for any hope of this carb delivering fuel in a proper manner. Another option is finding a similar carb for $10 on ebay and adapt. May have to change choke rod/plate from old to new. May have change throttle rod/plate or drill a new throttle link hole. I've used a coat hanger as a choke pull.

Look your carb over. Compare to "chainsaw carburetor" search on ebay. Poulan 1975 or 2375 or Husqvarna 142 (no purge circuit, tho) may work.

Oct 29, 2019#13

cpurvis

I am not an authority on diaphragm carbs but it looks to me like it goes concave side down.

Oct 30, 2019#14

G

ggratecc

dougand3 said:
You need to see needle move upward ~1mm when you push lever. Needle tip and seat are probably damaged or full of gunk/varnish. Need to remove screw, spring, lever and needle to see. Sounds like bad flooding. Spoon is welch plug. It must firmly attach all around the 3 holes. Rounded side up. Some use nail polish to secure seal but I'd rather have a new plug. 1st pic has 2 fuel pumps - just need 1. Fuel pump against carb, gasket against plate.

You must get a rb kit for any hope of this carb delivering fuel in a proper manner. Another option is finding a similar carb for $10 on ebay and adapt. May have to change choke rod/plate from old to new. May have change throttle rod/plate or drill a new throttle link hole. I've used a coat hanger as a choke pull.

Look your carb over. Compare to "chainsaw carburetor" search on ebay. Poulan 1975 or 2375 or Husqvarna 142 (no purge circuit, tho) may work.

Dougand3,
This is great, just the info I was looking for.
I did everything you mentioned in your first paragraph, but unfortunately have similar results, not starting, but less gas leaking. Thus I am giving up on it.
I found those Poulon compatible models you suggested, but think I will try this one from Amazon:
https://www.amazon.com/gp/product/B07MR29YS4/ref=ox_sc_act_title_1?smid=A19FM3LXB9B8NR&psc=1

Even if the choke plate control is on the wrong side, I like your idea of using a coat hanger!

I'll update you, when I get the new carb and installed.
Greg

Oct 31, 2019#15

dougand3

Yeah, that's the same carb and you get other stuff, too.

Nov 5, 2019#16

G

ggratecc

dougand3 said:
Yeah, that's the same carb and you get other stuff, too.

Dougand3,

See photo, the carb I bought did not fit on the cylinder side opening, due to the two alignment tits on cylinder do not have any place to go on the
carb! As you can see the original cylinder gasket is shown with the two tits.
So far I can't find a carb that will seat on the cylinder, any ideas? I keep looking at the C1Q body but can't find one like this.
thanks,
Greg

Nov 5, 2019#17

B

bertsmobile1

ggratecc said:
HI,
Current status: I removed the H/L limiter screws, then cleaned and reassembled carb using instructions from ZAMA, as far as gas pump side and nozzle side.
Put it back in the saw.
At first pumping the bulb did not work, so I pulled the rope a few times and then got fuel to flow with primer system.
Unfortunately, I can not get it to start at all now. Also, fuel is leaking out of the muffler when pulling rope.

stumped.
Greg

Going back to the beginning
The carb has to be airtight or it can not work.
The primer "sucks" air out of the system and "sucking" is not as effective as pushing so it can take 30+ pumps to get the fuel flowing.
The pin on the metering diaphragm points down to the lever.
The major difference with the diaphragms is the length of this pin.
The needle is closed by a spring and my guess is that you have omitted the spring or it has displaced sideways.
Never ever seen a cube carb with a locating pin on the face.
Are you sure that you have not misplaced a spacer ?

Nov 5, 2019#18

dougand3

So, the original carb has 2 special holes that accept with the 2 gasket retainer nipples? Then, carb can slam tight against the gasket all the way around? Seems like over-engineering. Doubt you'll find a new "nipple ready" carb.
Everybody else just puts 2 screws thru air filter housing and carb, mounts gasket on screws, then mounts carb by screwing in. Make sure sequence is intake impulse hole---gasket hole---carb impulse hole. Pic looked correct to flip carb on.
I'd trim nipples off flush with the rest of intake surface and mount carb. You need an airtight seal here. May need new gasket if old one is compressed too much.

Nov 6, 2019#19

G

ggratecc

dougand3 said:
So, the original carb has 2 special holes that accept with the 2 gasket retainer nipples? Then, carb can slam tight against the gasket all the way around? Seems like over-engineering. Doubt you'll find a new "nipple ready" carb.
Everybody else just puts 2 screws thru air filter housing and carb, mounts gasket on screws, then mounts carb by screwing in. Make sure sequence is intake impulse hole---gasket hole---carb impulse hole. Pic looked correct to flip carb on.
I'd trim nipples off flush with the rest of intake surface and mount carb. You need an airtight seal here. May need new gasket if old one is compressed too much.

Dougand3,
I came up with the same conclusion that I could grind off those two tits, the cylinder gasket is in excellent condition. It does seem all the impulse holes line up
as you said.
Q: if a bronze fuel line nipple is coming strait out of carb about 1/2", is it possible to bend it about 30 degrees?
thanks,
Greg

Nov 6, 2019#20

G

ggratecc

bertsmobile1 said:
Going back to the beginning
The carb has to be airtight or it can not work.
The primer "sucks" air out of the system and "sucking" is not as effective as pushing so it can take 30+ pumps to get the fuel flowing.
The pin on the metering diaphragm points down to the lever.
The major difference with the diaphragms is the length of this pin.
The needle is closed by a spring and my guess is that you have omitted the spring or it has displaced sideways.
Never ever seen a cube carb with a locating pin on the face.
Are you sure that you have not misplaced a spacer ?

HI,
I would love to repair this carb, feel I have come close; spring, lever, pin work great - deflect about 2mm when I press on lever.
I suspect there is some other problem that does not come in a rebuild kit... the nozzle check valve.

Nov 6, 2019#21

dougand3

Never bent a brass nozzle 30*....think it might collapse. Think about options to make it work...is it hitting plastic that can be cut away? Would a 90* nozzle work? You can change them but can be tricky.

Nov 6, 2019#22

B

bertsmobile1

No the fuel & return nozels are not bendable nor replaceable.
The size shape ,& direction of them is one of the things that demands 19,000 diferent carbs.

Did you take that manifold off at any point of time ?
have you owned it since new ?
Good chance that the manifold is on backwards.

Nov 8, 2019#23

G

ggratecc

bertsmobile1 said:
No the fuel & return nozels are not bendable nor replaceable.
The size shape ,& direction of them is one of the things that demands 19,000 diferent carbs.

Did you take that manifold off at any point of time ?
have you owned it since new ?
Good chance that the manifold is on backwards.[/QUOTE

thanks,
I got this used and was repairing it for a neighbor.
last week I purchased this :
https://smile.amazon.com/gp/product/B07MR29YS4/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1
A Trustsheer C1Q-W8 - $12.
I modified the chain saw so it would accept the carb (as is)!

Nov 8, 2019#24

G

ggratecc

dougand3 said:
Never bent a brass nozzle 30*....think it might collapse. Think about options to make it work...is it hitting plastic that can be cut away? Would a 90* nozzle work? You can change them but can be tricky.

All,
OK, the deed is done! Chain saw is working great with new carb:
https://smile.amazon.com/gp/product/B07MR29YS4/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1
Here are some photos:

I bought a new Dremel tool (which I have always wanted) and ground off the two tits on cylinder side of carb!
The choke control was on the opposite side of original , so I cut a hole in the filter cover and ran a small piece of wire to control it!
Then realized I need to shave some plastic case that was blocking the input fuel hose (no problem there).
Finally got carb on and realized the throttle linkage was getting stuck on the plastic case, thus I used the Dremmel again to shave off part of the throttle
linkage near the little hole of throttle control.

Then I decided to empty the fuel tank (actually did it before cutting and grinding), and found it had much debris as I flushed it out 4 times!
Listening to ya'll again, I put in a new HD premixed 50:1 fuel in tank.

closed choke and engine started up in about 15 pulls! Adjusted the idle and let it run in various angles for 10 min.
Turned it off, then reinstalled the chain. Started up on the second pull and took it to the backyard and cut down some branches.
I must say it works nearly like new.
As you can see it is missing a plastic tooth part on bottom to catch the log.

I want to especially thank you Doug for sticking with me on this! I learned much and got some satisfaction in the end.
best regards,
Greg

Nov 8, 2019#25

dougand3

That choke cable looks factory fresh. Good jury rigging job.
And the 3200 is a solid little limbing saw.

Nov 9, 2019#26

G

ggratecc

dougand3 said:
That choke cable looks factory fresh. Good jury rigging job.
And the 3200 is a solid little limbing saw.

and now it feels and cuts like a new $300 saw

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MAC 3200 will not start

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