Zama C1Q Nozzle Assembly Check valve replacement with pics

[SkippyKtm]

Just wanted to bump this thread once again with another update:
Using the drill press jig is a great idea, I have used it several times already and its much easier than using the arbor press.
I had a bunch of bad Walbro carbs that I previously couldn't fix, (WT-194, HD 17, 8, 18 carbs) and I found either the check valve itself was bad or the passageways that supply it were plugged. The passageways were still plugged because the USC couldn't clear them without pressing the valve out for access. The check valves only cost between $2.02 to $5.08 a piece; I buy them through my dealer who gets them from one of the common suppliers that I can't mention here (PM me if you want to know specifically who I got them from).
I'm batting a thousand so far on the Walbros and it sure beats spending $60 to $90 for a new carb...:msp_wink:

 

[PogoInTheWoods]

Just wanted to bump this thread once again with another update:
Using the drill press jig is a great idea, I have used it several times already and its much easier than using the arbor press.
I had a bunch of bad Walbro carbs that I previously couldn't fix, (WT-194, HD 17, 8, 18 carbs) and I found either the check valve itself was bad or the passageways that supply it were plugged. The passageways were still plugged because the USC couldn't clear them without pressing the valve out for access. The check valves only cost between $2.02 to $5.08 a piece; I buy them through my dealer who gets them from one of the common suppliers that I can't mention here (PM me if you want to know specifically who I got them from).
I'm batting a thousand so far on the Walbros and it sure beats spending $60 to $90 for a new carb...:msp_wink:

I get the drill press for the Zama's, (great idea....if you can pivot your vise to that angle!), but am I mistaken in thinking most Walbros have threaded nozzles making their replacement much easier anyway? (Think they may even be included in certain kits?)

Great thread, btw. Late rep shot headed at the OP and one coming your way for reviving the thread in light of the HD199 thread resurfacing as well.

edit: Well, shucks. Won't let me hit you, Skippy. Got the OP.

Out of curiosity, have you tried this method on an HD199 yet?

 

[trophyhunter]

:agree2: I rep'd him for you.

And I added some more, really good thread.

 

[SkippyKtm]

I get the drill press for the Zama's, (great idea....if you can pivot your vise to that angle!), but am I mistaken in thinking most Walbros have threaded nozzles making their replacement much easier anyway? (Think they may even be included in certain kits?)

I haven't seen any threaded ones yet(of course there's always a first!)

Great thread, btw. Late rep shot headed at the OP and one coming your way for reviving the thread in light of the HD199 thread resurfacing as well.

edit: Well, shucks. Won't let me hit you, Skippy. Got the OP.

Thanks for trying!

Out of curiosity, have you tried this method on an HD199 yet?

I haven't tried this on a HD199 yet, but I do plan on it, I do have some lying around in need...

Whoops! I forgot all about this post...
Answers are in quote boxes...

 

[maico490]

Good to see this has helped a few people. It was only when I read the HD199 thread the other day that I realised I had appeared in that crap fest! Still no real answer that I could work out. The two trimmer carbs that I replaced the nozzles on are still going fine. One has over 2000hrs on it now and we are still waiting for cheap Zama carbs here in the UK.
Thanks to everyone who has sent the rep and likes.

 

[wdfccf73]

Great thread!!! I'm interested in trying this instead of buying a new carb...
Check out my thread if you have any info you can suggest. Thanks!!!

 

[0x00]

finally!

finally the answer to why, no matter how many times I blow the body out with super high pressure air or jab at it with hardened steel wires it remains broken. I'll look into the check valves and fix em all now!

THANKS FOR THE POST and I just found the Zama tech guide online today too (it inspired me to revisit Arboristsite and look for more info).

note that the zama tech guide doesn't clearly show or mention the IDLE circuit check valve. at least the one I reviewed (quickly, I confess) didn't show it. it only showed the main jet check valve.

 

[nmurph]

Has anyone pressed the jet out of a a C3? I bought a couple of the jets, followed the instructions in this thread, and could not get them out using a drill press and rod.

 

[jerrycmorrow]

waking this thread up. hoping someone has the original pix and will post them.

 

[maico490]

This has been my first experience with the notorious check valves found on newer carbs. I've been chasing this problem on a FS450 trimmer for a while but luckily it has been between cuts on Water Authority sites. Searching here didn't throw up much but these carbs are used on lots of blowers, trimmers and smaller saws. The carb is a Zama C1Q-S34H which is fixed jet with only what appears to be an air screw (reverse thread) for idle adjustment.Symptoms were hard starting, inconsistant idle which couldn't be adjusted and would run out of fuel with an inch still left in the tank. When operating the primer bulb you could keep pumping without it becoming full and air bubbles were visible in the bulb. At full throttle everything was fine but as soon as you let off it would often stop dead. New lines, primer bulb,fuel filter and a rebuild kit did nothing. The answer was eventually found on Zama's excellent website: http://www.zamacarb.com/tips.html.
Before you do anything to a Zama carb I would recommend reading all the Service Tips. Especially DO NOT BLOW COMPRESSED AIR THROUGH A CARB WITH CHECK VALVES. It seems you also have to be careful with aerosol carb cleaner if directed straight into the valve with an extension tube.
So here's how it went:

The jet at the bottom of the metering chamber is the main jet which Zama call the "Nozzle Assembly Check Valve". Stihl call it the "Valve Jet".
The hole in the middle, which is normally hidden by the metering lever leads to the idle circuit. To test both circuits use a piece of hose over the jet and blow with your mouth. If clear then try to suck back. If you can the check valve is defective. This is bad news on the idle circuit as it means a new carb but the main jet can be replaced. Zama do a special tool but I managed to use a cheap drill press and one of my extensive collection of broken drill bits. If you have adjusting screws remove the H before starting.

It took a fair bit of fiddling to get everthing lined up and more force than I expected to get the nozzle to move. Here it is out and the new one:

The new one went in a lot more easily:

A few minutes of reassembly and it fired right up. Ticks over fine now and is responsive to the LA screw.

If you click to expand the above the pictures are back