Tillotson Carburetor Flooding

[louye2]

I recently rebuilt the Tillotson carburetor (HS 107B 605) in my Remington SL-9 chainsaw. I used the R3644 kit (replaces the RK-23HS).

I was pretty meticulous about following the instructions in the Tillotson HS service manual. When tried to startup the saw today, it ran for a few seconds and then died. I tried starting it a few times more, but it just does not start. I checked the carburetor compartment and it was flooded with about 1/4" of gas.

I've cleaned up the mess and let everything dry out for a few days. What do you suggest I do now?

Could this be a leaking fuel line problem? Should I focus on the inlet needle valve? Do I really need to remove the carburetor and do another rebuild? I'm pretty frustrated right now!

Thank you for your advice.

 

[PB]

If the flooding did not happen before the rebuild, then I would assume it is the result of the carb repair. You followed the HS manual so I am not sure what it could be. I would double check to see if you have the gaskets in the correct order and that your inlet lever is the correct height. For that carb, does the diaphragm hook to the lever or rest on top? If it is not hooked it will open the needle and flood. That is where I would start. I would go ahead and change the fuel line and filter too if those have not been changed recently. Good luck!

 

[machinisttx]

A few days ago I had a look at a saw for my wife's grandfather. He said it wouldn't run. I looked everything over and couldn't see any reason that it shouldn't be getting fuel, as the lines had been replaced with tygon in the not so distant past. I poured about a half tank of fuel in it to discover the duckbill in the fuel cap was faulty, so I swapped the cap. Then I saw the reason it wouldn't run....a tiny jet of fuel spraying from the fuel line, right where the barb ended at the carb. It was really baffling me why it would run and quit until I saw that.

My point is that there may be more than one problem, and you may have to fix the first one before you find the second. I would check the fuel line before I pulled the carb again, and then I'd bet on it being the metering lever.

 

[steverogers]

PB has good advice. The inlet lever I call it the "see-saw" can be a #####, check your assembly. When carb is off saw after rebuild I use a "Silverline" Vac/pressure hand pump tester. Depending on mfg.... but 4-10 lbs of press should pop open needle from seat. Did kit come with a template or gauge to set see-saw phram/needle height? I'm sure you dissay'd carb & blew it out? Don't loose small filter screen, might not have come in kit? Sometimes you might have to R&R welsh plugs...carefully... to blow out inaccessible passages. Also some saws, u can see in the Illus Parts List (IPL), have a reed valve. If it is not seating properly, debris, whatever, that could cause overpressure & carb leak. I've seen saws crankcase fill with liquid fuel so saw seemed 2 B seized. a crankcase drain plug would be nice but that prob is kinda uncommon. But if it happens you'll know. Also if u have a comp release make sure it works. I also use a primer bottle with tapered tip to check fuel delivery & any return lines & cap vent &/or check vlv (if so equipped) & integrity of lines & grommets. I don't know how 2 send pix 2 U from this site but a pix of my primer bottle is worth a thousand words, simple, fast, effective. Not as accurate as "Silverline" tester but cheap. Good Luck,... LoneSome PoleKat.

 

[steverogers]

machinisttx is right too. but my test with pressure & vac u can find the small stuff. Also if u do R&R a welsh plug it is advised to paint some nail polish or other sealer over it with your finger & let it set up & seal complete before puttin fuel thru carb Believe me it's worth the wait 4 it to set up & seal proper cause welsh plugs esp small ones r also a #####. L.P.

 

[steverogers]

Whoopsie, my bad! I didn't think before I typed B###H, DAG-NABBIT,... CON-SARNIT!
Ah recon I kin cuss like an ole prospector instead of a drunken sailor. Maybe?

 

[steverogers]

Yep looks lak ah kin. T,aint blocked out. DAG-STABBA-LAMMA-JAMMIT!

 

[cedarshark]

If the flooding did not happen before the rebuild, then I would assume it is the result of the carb repair. You followed the HS manual so I am not sure what it could be. I would double check to see if you have the gaskets in the correct order and that your inlet lever is the correct height. For that carb, does the diaphragm hook to the lever or rest on top? If it is not hooked it will open the needle and flood. That is where I would start. I would go ahead and change the fuel line and filter too if those have not been changed recently. Good luck!

Its been a while since I rebuilt a Tilly but I believe this diaphram "hooks" into the metering lever. If you pulled the top straight off the carb without unhooking the diaphram, you may have slightly bent the lever or deformed the rubber tip on the needle. Sure sounds like your needle is not sealing in the seat. Did you replace the needle or just install a diaphram/gasket kit ?

 

[half_full]

Its been a while since I rebuilt a Tilly but I believe this diaphram "hooks" into the metering lever.

yes. The 298A I did last night did. I've made that mistake before. You have to slide it into the metering lever rather than just setting it in place.

 

[jughead500]

Make sure it's gasket then diaphram.

 

[Junorr500]

I'm having the same problem with my till hs125. Did a rebuild, even reamed the needle seat flat again so the needle would seal, the seat was so corroded it looked like a funnel. Haven't done a pop test yet but it's next on my list. Fuel seems to pour out of the 3 little holes by the choke butterfly so maby the welch plug did not seal. Frustrating but educational project.

 

[cedarshark]

I'm having the same problem with my till hs125. Did a rebuild, even reamed the needle seat flat again so the needle would seal, the seat was so corroded it looked like a funnel. Haven't done a pop test yet but it's next on my list. Fuel seems to pour out of the 3 little holes by the choke butterfly so maby the welch plug did not seal. Frustrating but educational project.

The needle seat may be tapered from the factory. By reaming it flat...you may have worsened your problem and ruined the carb.

 

[Junorr500]

The needle seat may be tapered from the factory. By reaming it flat...you may have worsened your problem and ruined the carb.

Maby but the diagram of the carb shows the seat being flat. Either way its doing the same thing as before I reamed it. There is a port underneath the diagram beside where the lever spring is that slightly discoloured. Don't know what the port is for.

I'm also thinking that the low speed jet might have been tightened to hard and wrecked the seat.

Need to find a donor carb to see if the saw will run.

 

[cedarshark]

Maby but the diagram of the carb shows the seat being flat. Either way its doing the same thing as before I reamed it. There is a port underneath the diagram beside where the lever spring is that slightly discoloured. Don't know what the port is for.

I'm also thinking that the low speed jet might have been tightened to hard and wrecked the seat.

Need to find a donor carb to see if the saw will run.

When I rebuild a carb, I look at the needle under a magnifying glass. I cannot tell(w/ naked eye) if the rubber tip is worn or disfigured from ethanol. If it is not in almost perfect shape, it gets replaced. Those saws(non pro mostly) that getting the carb off is a PITA, get a new needle just to minimize the grief. I believe you have a good plan with a carb off a donor saw, preferably a running saw, to narrow down the problem.

 

[louye2]

Still flooding and not starting

Wow, lots of great advice. I did remove the carb again and checked the diaphragms and gaskets. Everything seems to be correct. The bottom diaphragm does hook into the control lever for the needle valve. I reinstalled the carb and it still floods.

Next, i'll check the fuel line and the connection to the carb housing. There is some kind of a metal flap there. The fuel line and cotton filter are probably original to the saw and should be replaced.

The Hi and Lo needle valves are very wet. Is there supposed be a tiny O ring in there? I don't remember seeing anything when I took the carb apart.

Finally, where does the vacuum hose go when doing the vacuum test?

Thank you for all your responses. I'll report back on the next steps.

 

[cedarshark]

Did you check to ensure your control lever is level with the floor of the carb. Sounds to me like your needle is not sealing or the lever is holding it open when it should be closed. Your problem is not getting gas to the carb..it is getting it through the carb in a correctly metered amount. Did you closely look at the rubber tip of the needle ?

 

[louye2]

The saga continues

I took the carburetor apart again and saw lots of flecks of orange paint on the little screen and in the needle valve hole. So, I cleaned everything out with compressed air and then decided to check under the Welch plug for more contamination. Well, I drilled too deeply into the Welch plug and now have a 3/32" hole going into the main chamber. Yikes, this is embarrassing.

Can I fill the hole with SuperGlue or some kind of automotive, gas-resistant silicone? What about the nail polish idea suggested for sealing the Welch plug?

Thanks again.

 

[cedarshark]

I have no idea how to fix this but you may have trashed the carb. Perhaps someone will offer some advice as to whether this can be fixed or not.

 

[pioneerguy600]

Your carb is now ruined, start looking for another of the same model series, your shafts, butterfly plates and levers will all swap over.

 

[cedarshark]

Your carb is now ruined, start looking for another of the same model series, your shafts, butterfly plates and levers will all swap over.

I was just now reviewing the Zama site for help on different issue but if you drill through the floor under the welsh plug on a Zama.....it's history. I am sure its the same for a Tilly.