066 Carb issues.

[betterbuilt]

I had one leaking in the plastic connector block in the fuel line. I pressure test everything before it goes on the saw, new, old or borrowed.
As JJ said the carbs for the 66's are pretty stout. Never had one that couldn't be corrected. ( clearly not a 200t carby)

I might also figure out a way to seal up the intake hose and pressure test that as well. Did I mention pressure test everything???

Are you sure you have the metal ring holding the intake manifold seating correctly and in place ?

I tried to pressure test everything:hmm3grin2orange:. I really thought I had seen picture of somebody doing that but, I guess I had got that wrong. I guess you never know if you don't try.

I'm pretty sure the metal ring is right.

I have been thinking it could be where the plastic block meets the fuel line. I have to wait for the shop to go through it now, but If they don't get it sorted I'll try to figure out how to pressure test the fuel lines to the carb. I'm also wondering about the impulse line where it connects to the carb body. Is anybody using any sealants on these connections?


Hey, thanks for the great info everybody.

 

[mtngun]

I'll try to figure out how to pressure test the fuel lines to the carb.

Hook vac to one end of the fuel line, plug the other end. Only takes a minute. Can detect leaks near the pass-thru that are otherwise hard to see.

No sealant necessary on the hoses.

Good luck, and keep us posted, so we can all learn.

 

[betterbuilt]

Well it turns out I had all the parts to build my own pop off tester. I had a blood pressure tester that I could rob parts from. I think I'm gonna go get my saw and try these tests on it. I'll post some pics of the homemade pop off tester.

Thanks again

 

[betterbuilt]

Well here it is.

I just need to get a reducer to fit the fitting on a carb now.

This was the set up I'm using to pressure test with. Now I can use it for two things.

 

[betterbuilt]

I found this in another Thread I hope Rusty doesn't mind.

How to test Diaphragm Carburetor without disassembly

QUICK TEST
Prove metering system works
Put 10psi on fuel inlet and see it hold there, (will creep down slowly) put tube on diaphragm vent hole and blow, watch inlet pressure drop
If it holds and drops that’s working

Test Main jet and Check Valve
Screw low Needle in until snug fit (Do Not Over tighten you will damage seat) then remove High Needle, get red nylon tube from WD40 spray can or similar and place in jet hole (takes some fiddling to get a good seal) when you think you are in the jet blow then suck you should feel the valve opening and closing as you do this (easy to blow harder to suck) if your not getting a response try sucking and blowing a little faster, if still not noticeable attach your WD40 and squirt some in (look in chamber and you should see it come out of the main jet, then try the suck blow test again (remember to clean the tube or you will get a mouthful)

Test Low Jets
Remove L needle put tube in and spray with WD40, look in chamber you should see it coming out of both holes.

NB
Using WD40 like this is OK for short periods (Don’t leave it in there for to long) I usually flush through with petrol after the test, A Quick blow on the supply tube will prove fuel can get there.
Put both needles back in till snug then back off 1 and ¼ turns (most working Carb’s will start at this setting)

General Notes
Main jet is in the centre of the chamber. Low Jets are each side of the throttle butterfly (Engine end). The H high needle (shorter one) is always closest to the air filter end and the L low needle (Longer one)is always closest to the engine. I made my pressure tester with a bicycle pump that had a gauge or you could use a car tyre pump and make an adaptor with an old valve stem and some fuel line (just remember not to go over 10psi or you might damage the diaphragm Zama) Walbro can go to pop off.

If it passes all these tests it should start and run now???

I also found this link for pop off testing.
http://www.eccarburetors.com/pdf/PopOff-Testing.pdf

 

[betterbuilt]

I pressure tested all my lines and they all passed but I bought new ones for the saw any ways.

I tried the pop off tester and my carb is failing the first test. It leaks back all the way. It leaks pretty slow but it continued to fall the whole way. I changed the needle with the old one and it did the same. I'm gonna change the spring in the morning.

 

[betterbuilt]

So I finally got back to my 066.

I got the carb to stop leaking back really fast by switching out the needle.

I put it back in the saw and tried to pressure test the fuel lines to the carb basically the same test I just did with the carb. It wont keep any pressure.

So I pulled the carb and did the pop test again and it wouldn't hold. Pulled the Carb apart and didn't see anything wrong. I put it back together and pop tested it again and it held. Put it back on the saw and it wouldn't hold again.

All the air leaking is in the carb.

Am I missing something?

 

[mtngun]

Flywheel OK ?

Keep us posted. I'm curious how this turns out.

 

[betterbuilt]

Flywheel OK ?

Keep us posted. I'm curious how this turns out.

I popped it off and it was fine.

 

[betterbuilt]

So I pulled the carb off again and it wouldn't hold pressure. I broke it down and put the old diaphram in it. It still wouldn't hold pressure. I wiggled the seat a little and it finally held again. I put it back in the saw and Bingo. I finally got it to hold pressure.

Finicky. SOB. I'm glad I ordered another carb.

I'm gonna put it together and see what it does.

 

[rupedoggy]

Possible solutions:
Gasket is wrong. Gasket against carb body, then diaphram!
Seat of needle in carb has a bad spot in it or junk in it. Take it out in good light and use magnifiers to look down in there for damage.
The little screen in the inlet may be partially plugged. If you clean it and then install it by shoving it in all the way, it only leaves a small area to filter and will plug right away. (this has nothing to do with pop off pressure but is good to know).
Set the fulcrum just a tad higher than specs. Seems to help with high speed and it sounds like you are running out of fuel.
Almost forgot. Some of thoses diaphrams use a "forky" fulcrum and others a "button". You have to use the correct one set to the correct height.

 

[betterbuilt]

By the way I have and old style aluminum flywheel I don't need any more if anyone needs it. It has the two key ways.

 

[betterbuilt]

Possible solutions:
Gasket is wrong. Gasket against carb body, then diaphram!
Seat of needle in carb has a bad spot in it or junk in it. Take it out in good light and use magnifiers to look down in there for damage.
The little screen in the inlet may be partially plugged. If you clean it and then install it by shoving it in all the way, it only leaves a small area to filter and will plug right away. (this has nothing to do with pop off pressure but is good to know).
Set the fulcrum just a tad higher than specs. Seems to help with high speed and it sounds like you are running out of fuel.

I cleaned it pretty good. I don't have a magnifier but I don't see anything in there.

I'm sure the gaskets are right but I bet your right there's something in there. I'm gonna take it off again and see if I can figure out whats messing the seal up.

I'm using the pop off as a fail safe right now. I don't trust this carb right now. The pop off is a good tool for telling you if your get a good seal that's for sure

 

[mtngun]

Some of thoses diaphrams use a "forky" fulcrum and others a "button". You have to use the correct one.

+1

There were several carbs used on the 066/660, some with the forky fulcrum and some with the button. If you use the wrong diaphragm, it'll run, but won't run right. Been there, done that.

 

[gink595]

Squirt the needle and seat with some WD-40 and see if it hold pressure or gas whichever is handy.

 

[betterbuilt]

+1

There were several carbs used on the 066/660, some with the forky fulcrum and some with the button. If you use the wrong diaphragm, it'll run, but won't run right. Been there, done that.

The kit I put in it, is the same as I took out. The diaphragm has the button. The lever has the fork but that's what I took out. It ran fine before this problem.

I bet I have a hybrid. I get the numbers off the carb and maybe someone can set me straight.

 

[mtngun]

I bet I have a hybrid. I get the numbers off the carb and maybe someone can set me straight.

Well, if you check the numbers, at least you know.

My 066 has a Walbro WJ69, and the diaphragm button has a groove that hooks into the fulcrum, what rupedoggy called "forky." It uses the K10-WJ kit.

From memory, the K15-WJ kit is used on some 066 carbs, and it has the smooth button. The K12-WJ kit may have a smooth button, too. You can't just order a "066 carb kit" because there is more than one kind.

Somehow I replaced the original forky diaphragm in my Oly 980's carb with the smooth button -- because I used the kit that Walbro had recommended, and I assumed Walbro must know best -- but it turned out that Walbro was wrong ! ! ! Anyway, the smooth button diaphragm would run, but it never ran right. Wouldn't hold tune, plug was wet and dark, apparently the needle valve wasn't sealing right and was flooding the carb. Switched back to a forky diaphragm and all was good.

So that's another thing -- the kit # recommended by Walbro is not always right ! There have been many variations of Walbro carbs, even Walbro seems to have a hard time keeping them straight.

Keep us posted, I enjoy a chainsaw detective problem. :msp_smile:

 

[betterbuilt]

I forgot to check the numbers on the carb.


Well I fired her up last night and it was closer, But its not right.

The other carb came in the mail so i put it on it. this time I had different problems. on the Lo side I couldn't get it to go lower then 3000 rpms. The high side seemed fine. I only tried it for a minute because it was getting dark. It seemed better but it wasn't idling right. I have to go to a job today so the saw will have to wait.

It's about time I learned more about carbs. I've been getting a free ride for a long time. This is something I wanted to learn more about just in case, but never needed to.