028 super

[Tbra]

I am hoping someone can give me some advice on my 028 super. The saw ran excellent for ~20 years before having trouble. Replaced it with another saw at the time but have recently gotten back into trying to get it back into commission. The saw will “pop” but won’t idle. Spritz gas into the carb and it will run until that gas is gone. It will try to run for a few seconds with a thumb over the carb but then will die.
So far i have done the following:
-checked the impulse line and carb boot for holes. Both were tested under pressure and vac with no leaks
-replaced both seals which hold pressure and vac-no leaks
-new air filter
-replaced the fuel line and filter
- replaced the gas tank breather
-new plug
-new rings in the piston and a new gasket for the cylinder. Cylinder looked great and no scoring. The saw has good compression.
-Rebuilt the original Walbro carb with the Walbro kit. Did a pressure check on the carb which holds pressure.
-bought a farmertec carb
-cleaned the muffler
-adjusted the L jet on both carbs from 1 turn to up to 3 times CCW with no difference.

Does anyone with more experience than me have any other ideas? I know it’s not pulling fuel but i can’t figure out why. Is there supposed to be any sort of check valve on the impulse line barb from the crank case or is that done within the carb. Any and all ideas/advice are greatly appreciated!

 

[Wood Doctor]

Looks like the problem is electrical, likely the ignition module or the connections, perhaps even the switch. You've done about everything else.

 

[Tbra]

I have pulled it over with the plug out and seems to spark pretty well. Also when i spray gas into the carb it will run for a few seconds until that fuel burns which makes me think it’s sparking okay.

 

[SteveSr]

I am hoping someone can give me some advice on my 028 super. The saw ran excellent for ~20 years before having trouble. Replaced it with another saw at the time but have recently gotten back into trying to get it back into commission. The saw will “pop” but won’t idle. Spritz gas into the carb and it will run until that gas is gone. It will try to run for a few seconds with a thumb over the carb but then will die.
So far i have done the following:
-checked the impulse line and carb boot for holes. Both were tested under pressure and vac with no leaks
-replaced both seals which hold pressure and vac-no leaks
-new air filter
-replaced the fuel line and filter
- replaced the gas tank breather
-new plug
-new rings in the piston and a new gasket for the cylinder. Cylinder looked great and no scoring. The saw has good compression.
-Rebuilt the original Walbro carb with the Walbro kit. Did a pressure check on the carb which holds pressure.
-bought a farmertec carb
-cleaned the muffler
-adjusted the L jet on both carbs from 1 turn to up to 3 times CCW with no difference.

Does anyone with more experience than me have any other ideas? I know it’s not pulling fuel but i can’t figure out why. Is there supposed to be any sort of check valve on the impulse line barb from the crank case or is that done within the carb. Any and all ideas/advice are greatly appreciated!

Did you put the carb back together with the gaskets and diaphragms in the right order? Both sides are different. If you used the new metering lever that came with the kit did you set it to the correct height?

 

[Tbra]

Thanks for the reply Steve. I will double check the carb. I figured it must be a carb issue but the brand new farmertec carb didn’t fix it either

 

[atpchas]

I figured it must be a carb issue but the brand new farmertec carb didn’t fix it either

Biggest problem with Chinese carbs when trying to isolate running issues is those carbs fail with distressing regularity. Best is if you can find a known good carb, one taken off a running saw.

 

[Gumneck]

I think SteveSR has it right. I would pull the metering diaphragm and make sure the lever is set correct. I just went through an 032 AV that would only run on choke, all test checked ok but the lever was just too low for the diaphragm to push the lever and open up the needle valve.

 

[Mad Professor]

Besides what Steve suggested on the carb. Were all the passages clear in the carb and the inlet screen clean. That is did you just replace gaskets/diaphragms/metering hardware or did you clean the carb out too? A gunked up inlet screen will do that.

 

[Tbra]

Thanks for all of the info guys. It indeed was the carb. I went through the OEM carb again checking the gaskets and the diaphragm. I used the new spring out of Chinese carb in the Walbro and made sure to set the lever appropriately. Put it back together and it fired right up. I ran it pretty hard today and it was cutting well. I’m running it a bit on the rich side with lower ratio fuel to oil ratio to give the new rings more oil to get seated. Thanks for all the replies!