Discontinued zama carburetor c1u-m35a mcculloch blower

mr.farmall

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  • / Discontinued zama carburetor c1u-m35a mcculloch blower
McCulloch leaf blower model " MAC 320BV" or 320BV. (blower vac). On the engine their is a label " C134" along with "CT M 32cc SMH032UB24RA EM".
I have no idea who made the engine!!
The engine starts right up runs as if it is flooding, then after about 1 minute, floods and wont start again until the plug is dried off.
I have disassembled the carb and cleaned it with an ultrasonic cleaner time after time. no change, it starts but won't rev up and then floods out after about 45 seconds with full throttle. let off the throttle and it kills.
The jets are turned most of the way to bottoming out, only 1/2 turn open. (this model has adjustable high and low needles).
This model carburetor, "c1u-m35a" is discontinued and not to be found in the market.
Zama makes a lot of variations of the "C1U" body of the carburetors, I was wondering if they are the same body and only have different attachments like the choke lever, throttle controls and such. If so I would like to order one and change my attachments over to the new body. But I don't know enough about them to be able to make that decision.
Maybe some one can point me on how to fix this flooding issue. Hopefully someone reading this can guide me a little or give a help on how to solve this problem and make it run again.
thanks in advance
Rex
 
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  • / Discontinued zama carburetor c1u-m35a mcculloch blower
The jets as you speak of should be out more than a 1/2 turn........... Something is up with that........ Some models are different than others...... 1 and 1/2 on each one or a lil more......

The one closest to the air filter is the high side ...... That is adjusted while the throttle is pinned wide open,, With a good ear.....

The other one is the low speed screw...... Do you have the right driver to adjust those pesky screws ????
 

bertsmobile1

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  • / Discontinued zama carburetor c1u-m35a mcculloch blower
Did you put a kit through the carb ?
Flooding can be caused by a perforated metering diaphragm. the metering diaphragm in the wrong place or upside down.
The metering diaphragm set to the wrong height, a loose or missing diaphragm spring a badly worn damaged or dirty needle or needle jet.

How much do you actually know about cube carbs ?

And yes you get a current carb and swap the throttle & choke .
 

Boobala

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  • / Discontinued zama carburetor c1u-m35a mcculloch blower
I just replaced my Zama carb on my Stihl FS-90R last week, my particular model was also discontinued, but I found a replacement at the local mower shop, ( they had the cross-reference by Stihl P/N, info for Zama carbs ) I did have to adjust the jets but after awhile I had it running like new, my carb is also a C1U - BASE model, I did some diggin for ya, and found your kit #s .....

Carb kit # RB-29 ..... Gasket & Diaphragm kit # GND-12

see info below, I had to shrink the pages to fit, but you can enlarge them to make out the info. I'll try to dig thru my "files" & find out more if I can, will post if I do....... you can search the web and find prices on the kits and availability, also a good chainsaw site for McCulloch parts is ( lilredbarn.net) they helped me with my McCulloch 3200 a good time back.

https://www.zamacarb.com/pdfs/TechGuide_2007.pdf

https://www.zamacarb.com/carburetors/767

https://www.zamacarb.com/assets/pdfs/carbtypes/c1u.pdf

https://www.zamacarb.com/carburetors/types/5

https://www.lawnmowerpros.com/lawn-mower-parts-database-search.asp?searchterm=RB-29

https://www.lilredbarn.net/

View attachment 38972..View attachment 38973..
 
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mr.farmall

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  • / Discontinued zama carburetor c1u-m35a mcculloch blower
Boobala;302871 Carb kit # RB-29 ..... Gasket & Diaphragm kit # GND-12 see info below said:
Thanks so much for the info. the instructional guide is great. answeres many questions. I think I'll start with the carb kit.
thanks
Rex
 

mr.farmall

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  • / Discontinued zama carburetor c1u-m35a mcculloch blower
Did you put a kit through the carb ?
Flooding can be caused by a perforated metering diaphragm. the metering diaphragm in the wrong place or upside down.
The metering diaphragm set to the wrong height, a loose or missing diaphragm spring a badly worn damaged or dirty needle or needle jet.

And yes you get a current carb and swap the throttle & choke .

with the info posted on this thread, I have a lot to learn and do. I'll start with the rebuild kit and go from there.
I would imagine that any of the above could be the problem. thanks for helping.
if all fails, I'll get back with you on buying a replacement and swaping parts. good to know that it can be done. This is reall a great blower and I hate to see it stop working.
thanks Rex
 

bertsmobile1

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  • / Discontinued zama carburetor c1u-m35a mcculloch blower
with the info posted on this thread, I have a lot to learn and do. I'll start with the rebuild kit and go from there.
I would imagine that any of the above could be the problem. thanks for helping.
if all fails, I'll get back with you on buying a replacement and swaping parts. good to know that it can be done. This is reall a great blower and I hate to see it stop working.
thanks Rex

Walbro have several manuals on line.
They are a little hard to find as the links are down the bottom right corner of the pages.
Once you know how they actually work repairing them becomes a lot easier.
Walbro -Zama - Tillotsen - Ru Zing _ they basically all work the same, either butterfly or rotary valve.
So one manual cover all of them.

Also remember a hand held fuel tank runs under pressure.
The pump does not draw the fuel into the carb from the tank, the pressure from the returned fuel forces the fuel to the pump, much like the old outboards where you had to keep pumping air into the tank.
Now here is the rub.
the fuel cap usually has a one way valve ( air in ) and the tank usually has a vent to let excess pressure out.
If the tank vent is not working the tank will over pressurize and force too much fuel into the carb
 
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mr.farmall

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  • / Discontinued zama carburetor c1u-m35a mcculloch blower
Also remember a hand held fuel tank runs under pressure.
The pump does not draw the fuel into the carb from the tank, the pressure from the returned fuel forces the fuel to the pump, much like the old outboards where you had to keep pumping air into the tank.
Now here is the rub.
the fuel cap usually has a one way valve ( air in ) and the tank usually has a vent to let excess pressure out.
If the tankvent is not working the tans will over pressurize and force too much fuel into the carb

What a timely piece of info. I had no idea that the tanks were pressurized, but makes since. I was thinking the carbs were fuel pumps like some of the old B&S carbs were. I think I'll replace hoses along with the carb kit.
thanks again
Rex
 
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