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Discontinued zama carburetor c1u-m35a mcculloch blower
#1
M
mr.farmall
M
mr.farmall
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
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
#2
Boudreaux In Eunice La.
Boudreaux In Eunice La.
Did you put a new kit in it ???
#3
Boudreaux In Eunice La.
Boudreaux In Eunice La.
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 ????
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 ????
#4
B
bertsmobile1
B
bertsmobile1
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 .
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 .
#5
Boobala
Boobala
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..
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..
#6
Boobala
Boobala
Found a few more items..........
https://www.ebay.com/itm/322410-01-...015108&hash=item441ca7353e:g:hd8AAOSwPW9a4ULH
http://www.carburetion.com/products/productdetails.aspx?part=KT-RB-29
...
https://www.ebay.com/itm/322410-01-...015108&hash=item441ca7353e:g:hd8AAOSwPW9a4ULH
http://www.carburetion.com/products/productdetails.aspx?part=KT-RB-29
...
#7
M
mr.farmall
M
mr.farmall
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
#8
M
mr.farmall
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
M
mr.farmall
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
#9
B
bertsmobile1
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
B
bertsmobile1
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
#10
M
mr.farmall
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
M
mr.farmall
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
#11
B
bertsmobile1
B
bertsmobile1
Be careful doing that and make sure you get the right tube.
The pick up line is heavy walled and the return line is generally thin walled but that is not so important.
The tube must be a tight fit in the tank, if you can pull it through easily it is too thin.
Use the butt end of drill bits to measure the diameter, it steps up in 1/32" incriments.
And very important.
make sure you fit Tygon tubing ( or equivalent ) bought from a real reputable mower parts suppler.
I get emails daily from internet suppliers trying to sell me "PVC fuel line in popular see through yellow colour".
The genuine tube is very expensive and charged by the inch.
I pay around $ 10 to $ 20 a foot ( Aus) wholesale for genuine TYGON tubing
Stens have an equivalent but it is only 30% cheaper.
We have had a few people burned because the tubing on their cheap store branded trimmers leaked fuel all over it and in some cases the operator and then ignited.
The pick up line is heavy walled and the return line is generally thin walled but that is not so important.
The tube must be a tight fit in the tank, if you can pull it through easily it is too thin.
Use the butt end of drill bits to measure the diameter, it steps up in 1/32" incriments.
And very important.
make sure you fit Tygon tubing ( or equivalent ) bought from a real reputable mower parts suppler.
I get emails daily from internet suppliers trying to sell me "PVC fuel line in popular see through yellow colour".
The genuine tube is very expensive and charged by the inch.
I pay around $ 10 to $ 20 a foot ( Aus) wholesale for genuine TYGON tubing
Stens have an equivalent but it is only 30% cheaper.
We have had a few people burned because the tubing on their cheap store branded trimmers leaked fuel all over it and in some cases the operator and then ignited.
#12
primerbulb120
Not to be antagonistic, but there are several factors that prevent this theory of operation from being possible.
1. To begin with, it's not possible for most older fuel systems to operate on pressure from the return line, because the majority of older handhelds have no fuel return line.
2. On units that do have a return line, the return line is part of the air purge/primer bulb circuit, and is only used to return air and fuel to the tank when the engine is being primed.
3. There is no reason to have both an intake vent and a vent to release excess pressure. If the fuel tank runs under pressure, why does it need a one way valve to let air in?
4. The majority of handhelds have no pressure relief vent anyway. There's only one vent, and it's a one way vent that allows air in to take the place of the fuel used by the engine. The only way that the tank can over pressurize is if the fuel gets heated and expands, which will pop off the needle valve and over pressurize the carb.
Theory of operation, from Zama: https://www.zamacarb.com/page/carburetor-systems-operations
primerbulb120
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
Not to be antagonistic, but there are several factors that prevent this theory of operation from being possible.
1. To begin with, it's not possible for most older fuel systems to operate on pressure from the return line, because the majority of older handhelds have no fuel return line.
2. On units that do have a return line, the return line is part of the air purge/primer bulb circuit, and is only used to return air and fuel to the tank when the engine is being primed.
3. There is no reason to have both an intake vent and a vent to release excess pressure. If the fuel tank runs under pressure, why does it need a one way valve to let air in?
4. The majority of handhelds have no pressure relief vent anyway. There's only one vent, and it's a one way vent that allows air in to take the place of the fuel used by the engine. The only way that the tank can over pressurize is if the fuel gets heated and expands, which will pop off the needle valve and over pressurize the carb.
Theory of operation, from Zama: https://www.zamacarb.com/page/carburetor-systems-operations
#13
primerbulb120
$10 per foot is outrageous. I use Oregon brand fuel line, and it costs me about $20 for a 50 foot roll...
primerbulb120
Be careful doing that and make sure you get the right tube.
The pick up line is heavy walled and the return line is generally thin walled but that is not so important.
The tube must be a tight fit in the tank, if you can pull it through easily it is too thin.
Use the butt end of drill bits to measure the diameter, it steps up in 1/32" incriments.
And very important.
make sure you fit Tygon tubing ( or equivalent ) bought from a real reputable mower parts suppler.
I get emails daily from internet suppliers trying to sell me "PVC fuel line in popular see through yellow colour".
The genuine tube is very expensive and charged by the inch.
I pay around $ 10 to $ 20 a foot ( Aus) wholesale for genuine TYGON tubing
Stens have an equivalent but it is only 30% cheaper.
We have had a few people burned because the tubing on their cheap store branded trimmers leaked fuel all over it and in some cases the operator and then ignited.
$10 per foot is outrageous. I use Oregon brand fuel line, and it costs me about $20 for a 50 foot roll...
#14
B
bertsmobile1
St Germain, the makes do not sell Tygon in 50' rolls.
They market 5' rolls in plastic bag
10' rolls in dispenser carton
20' rolls in dispenser cartons
200' rolls on spindle
$ 20 for a 50' roll sounds more like standard 1/4" butyl lined, single cotton insertion neoprene tube as used on mowers , not hand helds.
B
bertsmobile1
$10 per foot is outrageous. I use Oregon brand fuel line, and it costs me about $20 for a 50 foot roll...
St Germain, the makes do not sell Tygon in 50' rolls.
They market 5' rolls in plastic bag
10' rolls in dispenser carton
20' rolls in dispenser cartons
200' rolls on spindle
$ 20 for a 50' roll sounds more like standard 1/4" butyl lined, single cotton insertion neoprene tube as used on mowers , not hand helds.
#15
primerbulb120
primerbulb120
Oregon sells Tygon fuel line. They have their own brand, and premium Tygon...
#16
B
bertsmobile1
Next time your get a MODERN hand held into your shop, and in preference one fitted with a CQ Zama, run it for 5 minutes then open the fuel cap.
You will find it is pressureised and should be in the order of 5 to 10 psi.
Old carbs had a bigger and stronger pump , a bigger metering chamber and 2 internal check valves which you used to access via the welch plugs that are no longer fitted.
If you go & check the 2 stroke diagnosis videos that Joe Pace has uploaded you will see that Husqvarna fuel tanks are tested under both pressure & vacuum .
A very large number of fuel caps used by Husqvarna have 2 valves in them, an inlet & an outlet.
The Echo fuel tank vent is an exhaust vent and nearly all Stihls have an inlet in the cap and an outlet from the tank.
If you are still in doubt, pull the return line out of a chain saw and run a long line down to a catch bottle, stick a plug in the return hole in the tank.
The saw will start & run, but it will be very sluggish under acceleration and most will not get to full speed.
Trimmers are not such a problem because they are generally used right way up but chain saws & blowers get used al all sorts of funny angles so really need the fuel pressure.
I have just done a pile of cheap imported chain saws that use PVC fuel tube.
Once they get a few ears old the fuel lines shrink & become loose in the tanks.
In that condition they will not even start.
If you want to check this search Ross brand chainsaws and read the customer comments.
I have fixed dozens of these cause the local hardwear chain flogged them off really cheap.
All that needs to be done is to fit new fuel lines that are airtight.
B
bertsmobile1
Not to be antagonistic, but there are several factors that prevent this theory of operation from being possible.
1. To begin with, it's not possible for most older fuel systems to operate on pressure from the return line, because the majority of older handhelds have no fuel return line.
2. On units that do have a return line, the return line is part of the air purge/primer bulb circuit, and is only used to return air and fuel to the tank when the engine is being primed.
3. There is no reason to have both an intake vent and a vent to release excess pressure. If the fuel tank runs under pressure, why does it need a one way valve to let air in?
4. The majority of handhelds have no pressure relief vent anyway. There's only one vent, and it's a one way vent that allows air in to take the place of the fuel used by the engine. The only way that the tank can over pressurize is if the fuel gets heated and expands, which will pop off the needle valve and over pressurize the carb.
Theory of operation, from Zama: https://www.zamacarb.com/page/carburetor-systems-operations
Next time your get a MODERN hand held into your shop, and in preference one fitted with a CQ Zama, run it for 5 minutes then open the fuel cap.
You will find it is pressureised and should be in the order of 5 to 10 psi.
Old carbs had a bigger and stronger pump , a bigger metering chamber and 2 internal check valves which you used to access via the welch plugs that are no longer fitted.
If you go & check the 2 stroke diagnosis videos that Joe Pace has uploaded you will see that Husqvarna fuel tanks are tested under both pressure & vacuum .
A very large number of fuel caps used by Husqvarna have 2 valves in them, an inlet & an outlet.
The Echo fuel tank vent is an exhaust vent and nearly all Stihls have an inlet in the cap and an outlet from the tank.
If you are still in doubt, pull the return line out of a chain saw and run a long line down to a catch bottle, stick a plug in the return hole in the tank.
The saw will start & run, but it will be very sluggish under acceleration and most will not get to full speed.
Trimmers are not such a problem because they are generally used right way up but chain saws & blowers get used al all sorts of funny angles so really need the fuel pressure.
I have just done a pile of cheap imported chain saws that use PVC fuel tube.
Once they get a few ears old the fuel lines shrink & become loose in the tanks.
In that condition they will not even start.
If you want to check this search Ross brand chainsaws and read the customer comments.
I have fixed dozens of these cause the local hardwear chain flogged them off really cheap.
All that needs to be done is to fit new fuel lines that are airtight.
#17
I
intimidator
I am having the same problem as the original poster. I installed a new gasket kit and still having a flooding issue. What would be the correct current carb I can use to swap.
I
intimidator
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 .
I am having the same problem as the original poster. I installed a new gasket kit and still having a flooding issue. What would be the correct current carb I can use to swap.
#18
Boobala
intimidator ... NOT trying to be rude, but you are HI-Jacking this fellas thread, it becomes chaos when folks do that, you have folks trying to help 2 different people on 1 thread you needed to start a new thread , nuff said on that !..
the information you seek is posted in post #5 & #6 of this thread posting, go to this page, (below) and click on the items listed under parts and service, then SCROLL DOWN on that page and there's the info, if you can't do a little research of your own, take the machine to a reputable dealer, I'm not going to hold your hand and walk you through it, I've already went beyond what most other folks would do, as it is .
https://www.zamacarb.com/page/products
We do everything POSSIBLE :
The IMPOSSIBLE, takes a little longer :
MIRACLES are by appointment only :
Boobala
I am having the same problem as the original poster. I installed a new gasket kit and still having a flooding issue. What would be the correct current carb I can use to swap.
intimidator ... NOT trying to be rude, but you are HI-Jacking this fellas thread, it becomes chaos when folks do that, you have folks trying to help 2 different people on 1 thread you needed to start a new thread , nuff said on that !..
the information you seek is posted in post #5 & #6 of this thread posting, go to this page, (below) and click on the items listed under parts and service, then SCROLL DOWN on that page and there's the info, if you can't do a little research of your own, take the machine to a reputable dealer, I'm not going to hold your hand and walk you through it, I've already went beyond what most other folks would do, as it is .
https://www.zamacarb.com/page/products
We do everything POSSIBLE :
The IMPOSSIBLE, takes a little longer :
MIRACLES are by appointment only :
#19
B
bertsmobile1
If you can find a parts book look at what carb is fitted to it and any others in the same series.
Often makers will use several different carbs according to what was available at the time.
Failing that ask Zama about what carb will replace yours .
Usually the difference within a series ( C1Q M35) will only be the throttle & choke shafts which have different ends
They are easy to replace, but the screw holding the butterflys in place must be loktited or soldered in place cause they have a habit of being ingested.
Having said that flooding in a cube carb is nearly always due to either a blocked fuel return or tank vent causing over pressurization
or
Incorrect needle height / worn needle or spring.
To test the operation you really need both a vacuum meter & a pressure meter.
Finally are you sure that the engine is flooding ?
A dirty spark plug , faulty ignition module ( including HT lead & cap) , blocked vent , shoring ground wire or cut out switch can all produce symptoms very similar to flooding.
Cube carbs rarely fail by flooding.
Check out the videos mentioned in a previous post to the original poster.
You can look at Taryl Fixes all , although he does not do much on cube carbs & Donny Boy.
Any video that mentions about "Pop off Pressure " should be ignored .
B
bertsmobile1
I am having the same problem as the original poster. I installed a new gasket kit and still having a flooding issue. What would be the correct current carb I can use to swap.
If you can find a parts book look at what carb is fitted to it and any others in the same series.
Often makers will use several different carbs according to what was available at the time.
Failing that ask Zama about what carb will replace yours .
Usually the difference within a series ( C1Q M35) will only be the throttle & choke shafts which have different ends
They are easy to replace, but the screw holding the butterflys in place must be loktited or soldered in place cause they have a habit of being ingested.
Having said that flooding in a cube carb is nearly always due to either a blocked fuel return or tank vent causing over pressurization
or
Incorrect needle height / worn needle or spring.
To test the operation you really need both a vacuum meter & a pressure meter.
Finally are you sure that the engine is flooding ?
A dirty spark plug , faulty ignition module ( including HT lead & cap) , blocked vent , shoring ground wire or cut out switch can all produce symptoms very similar to flooding.
Cube carbs rarely fail by flooding.
Check out the videos mentioned in a previous post to the original poster.
You can look at Taryl Fixes all , although he does not do much on cube carbs & Donny Boy.
Any video that mentions about "Pop off Pressure " should be ignored .