Super EZ fuel issues

[JW51]

Bought a SEZ a while back as a project. Finally got around to messing with it this weekend. When I first got it, it’d start reluctantly, but flood out very quickly and die. The metering lever height was all jacked up so I figured a kit would fix it. Was very careful when I set the height. I have good spark and what feels like excellent compression.

It does start, run and rev now, but a few issues remain:

1) Fuel is leaking from somewhere into the air box. Presumably the carb but I can’t see anything obvious.

2) It idles ok, for a while, maybe 30 secs to a minute, then dies suddenly. Actually revs up quite well.

3) I get little to no response from the low speed screw. It doesn’t idle any better or worse even when fully turned in and seated. I’ve been testing it at 1 to 1.25 turns out.

3) I really fought getting the throttle linkage off and back on again. Is there a trick? Upon reassembly I actually took apart the handle to loosen that end, attached to the carb, and put the handle back together. I’m not completely sure I got the compression release thing correct. Is it supposed to hold the throttle slightly open? At present, it does not, but the saw starts anyway.

 

[sawnami]

Which side of the metering diaphragm is your gasket on?

Sent from my SM-N950U using Tapatalk

 

[JW51]

Gasket against carb body. Diaphragm between gasket and cover.

 

[JW51]

Haven’t removed the carb yet, but did a little more test running to further investigate. Looks to me like fuel is coming out of the throttle bore itself. Choke plate and surrounding area is wet. Muffler wet as well but I assume it’s seeping there from above. And I assume the poor idle is due to rich running/ flooding. (Lots of assumptions with scant evidence!)

I’ve seen some mention of a little check valve on these HDC carbs that sometimes needs replaced. Would a faulty check valve produce this kind of symptom?

 

[lostone]

OK, several things are at play here.

First, leaking gas into air box is probably pump side diaphragm is toast or screw loose. I also recommend putting in a new fuel line and grommet, for that go to Leon's chainsaw repair. He offers a Tygon hose/grommet kit that works great.

Sounds like you need a rebuild badly, K10-HDC kit, should solve the leak and the poor running condition, Ultrasonic cleaner is fantastic for cleaning a carb if you can/want, Harbor freights ultrasonic works fine.

Throttle linkage comes off easy, pull the handle screws and remove the trigger from it's pin it is on.

Pull muffler cover and see how much carbon is built up in there, If you have to remove the carbon make sure the piston is covering the port and use a plastic or wood device to scrape it off and make sure all of the loose is out before moving the piston to an open position (this is how Homelite recommends removing it in their manual).

I recommend the Walbro kit over the aftermarket kits, be careful when you pull the plate to use the correct gasket inside (there are two different ones, match up what is in there). There was the Walbro HDC-44 and HDC-64 carb used on these saws, the HDC-64 was an option and rare to see on one of them but they both use the same rebuild kit.

 

[lostone]

Leon's chainsaw repair EZ/SEZ page.

Leon's site with specs and manuals to work on EZ/SEZ etc.

If you have to do anything to the ignition side make sure which version you have, They used two versions. Wico and Phelon, the flywheel, points, condensor and coil are different between them and they don't interchange.

 

[JW51]

OK, several things are at play here.

First, leaking gas into air box is probably pump side diaphragm is toast or screw loose. I also recommend putting in a new fuel line and grommet, for that go to Leon's chainsaw repair. He offers a Tygon hose/grommet kit that works great.

Sounds like you need a rebuild badly, K10-HDC kit, should solve the leak and the poor running condition, Ultrasonic cleaner is fantastic for cleaning a carb if you can/want, Harbor freights ultrasonic works fine.

Throttle linkage comes off easy, pull the handle screws and remove the trigger from it's pin it is on.

Pull muffler cover and see how much carbon is built up in there, If you have to remove the carbon make sure the piston is covering the port and use a plastic or wood device to scrape it off and make sure all of the loose is out before moving the piston to an open position (this is how Homelite recommends removing it in their manual).

I recommend the Walbro kit over the aftermarket kits, be careful when you pull the plate to use the correct gasket inside (there are two different ones, match up what is in there). There was the Walbro HDC-44 and HDC-64 carb used on these saws, the HDC-64 was an option and rare to see on one of them but they both use the same rebuild kit.

Good stuff thanks. The fuel line had been recently replaced with new Tygon before I got it.

It also came to me with a couple new kits and an extra carb. One walbro kit and one AM. Both had been opened so hard to say 100% if I got the right stuff installed when I rebuilt the first time.

Perhaps I’ll source a new kit just so I know for certain.

Also, the little copper/brass screen that covers the mystery check valve is buggered up and pushed in slightly. Not sure if I did it or if was already like that. What are the implications of that?

 

[lostone]

You can find the parts on Leon's, he has new screens. If you are talking about the oil pickup screen. Again if you have only the manual oiler you will have one of them if you have the two separate oiler (auto and manual) then there will be two of the same screen. Mine came off in the tank and I just left it in there and got a new one and put on it. They are cheap.

 

[JW51]

You can find the parts on Leon's, he has new screens. If you are talking about the oil pickup screen. Again if you have only the manual oiler you will have one of them if you have the two separate oiler (auto and manual) then there will be two of the same screen. Mine came off in the tank and I just left it in there and got a new one and put on it. They are cheap.

I was referring to the screen covering the check valve inside the carb. Looks like it’s held in with a little ring of some sort.

 

[pioneerguy600]

The reed valve comes to mind, if it is not seating tight it will cause erratic idle and spitback.

 

[lostone]

I was referring to the screen covering the check valve inside the carb. Looks like it’s held in with a little ring of some sort.

It is, There will be a new ring and screen with the kit. These are very touchy carbs in my opinion and a very slight change in the jets affects them a lot, so go easy when adjusting it. They aren't like the SDC's which seemed to be more forgiving.

Also look and see if it has the spark arrestor screen in place, The manual Homelite put out or one of the follow ups talks about how these saws where prone to carbon build up.

Also when rebuilding it the reason I recommend the Walbro brand kit is some of the aftermarket have a different button in the center of the diaphragm and it is longer so it will unseat the valve if you set the lever where it calls for it to be, I found this out when doing a pressure test and then noticed the difference between the original and the aftermarket one. I ordered a Walbro and that solved the issue. I know I could have set it by pressure rather than by height but that would limit the travel on the needle and I wanted it to be able to open more.

One last thing to look for, pull the bar cover off and release chain tension and see if there is any play in the PTO side bearing.

 

[JW51]

The reed valve comes to mind, if it is not seating tight it will cause erratic idle and spitback.

Reed block is right behind the carb I guess. But how far do I have to disassemble to have a look at the reeds?

 

[pioneerguy600]

Reed block is right behind the carb I guess. But how far do I have to disassemble to have a look at the reeds?

You may have to go all the way to the block/cylinder, check the gaskets while you are in there as they are likely soft/soggy by now.

 

[lostone]

Also keep in mind it's a one piece gasket so be careful. It does both the intake and cylinder. If it tears you can take a new one and cut the top piece off and just use that instead of taking the cylinder off to replace the gasket.

 

[lostone]

I love the SEZ. I got into to big of a hurry when I replaced the seals on one of mine and now I have to go back into it and replace a bearing, well I will replace both of them. Even with a slight amount of play it still runs pretty good but I want it running perfect.

Full wrap, all new anti vibe, carb rebuild, new fuel line, fuel cap valve replaced, new oil lines, new oil cap, new air filter, new points/condensor, new spark plug, new seals, converted to rim and drum etc. I got lucky enough to find a HDC-64 carb I will be putting on this one.Little saw is torqie as all get out.

 

[JW51]

I love the SEZ. I got into to big of a hurry when I replaced the seals on one of mine and now I have to go back into it and replace a bearing, well I will replace both of them. Even with a slight amount of play it still runs pretty good but I want it running perfect.

Full wrap, all new anti vibe, carb rebuild, new fuel line, fuel cap valve replaced, new oil lines, new oil cap, new air filter, new points/condensor, new spark plug, new seals, converted to rim and drum etc. I got lucky enough to find a HDC-64 carb I will be putting on this one.Little saw is torqie as all get out.

How is the HDC-64 carb different from the other?

A brief look at my two carbs last night..didn’t reveal 44 or 64. I see the HDC. And some other part numbers or model numbers.

 

[lostone]

HDC-64 has a larger venturi, It will be marked HDC-64. If yours says HDC-4 then its a 44.

 

[JW51]

Still wrestling with the SEZ. Actually switched it to a different carb last night. Paid special attention to the metering lever height and getting the correct circuit plate gasket. Rigged up a very crude pressure tester to check needle function and it seemed OK.

Still getting some spit back or leaking into the air box, but seems like less than before. Ran out of time to fiddle with tuning, but symptoms still very similar. Will start and rev. Won’t idle long at all. Screws both 1 turn out.

Where to go from here....

1). One part of carb that hasn’t been replaced is the check valve. What kind of symptoms would a faulty once cause?

2). I suppose I’m gonna go hunting for an air leak. Probably spraying carb cleaner at first and then maybe a vac/pressure test.

I’ve done vac/pressure test on an 028 Stihl. Blocked off muffler and carb and did it through the pulse line. Where would be the easiest place to hook up on this saw?

 

[Tom B.]

Leon's chainsaw something on YouTube just put out a video on a homelite. Very good info. My super mini has the same issue.

 

[lostone]

Spit back is a Reed valve issue.