Walbro SDC Issues

[saxman]

I have a Homelite XL102 that has a SDC carb that I have rebuilt but it still won't run. I removed the carb and installed new gaskets and a diaphragm after using carb cleaner and air to blow it out. The saw will run only if primed with mix. I have rebuilt many carbs and never had this much trouble but it seems I don't have much luck with the SDC. Are there any tricks or something special about this model I should know? Any words of advice would be appreciated

Steve

 

[mattinky]

Have you checked the condition of the fuel line? they can look good but have holes in them, fuel filter? Have you double checked your metering lever height and that the gaskets are in the right order?

 

[Eccentric]

Did you replace the screen in the carb body?

 

[saxman]

It has a new fuel line and I did not replace the screen

 

[DSS]

Take the screen out and look, could be full of crud under it. An SDC is a very good carb.

 

[machinisttx]

Have you checked the condition of the fuel line? they can look good but have holes in them, fuel filter? Have you double checked your metering lever height and that the gaskets are in the right order?

I'd go with this. I never mess with the screen, just pull the metering lever and blow carb cleaner through to clear any gunk.

 

[DSS]

It takes 10 seconds to pull that screen.

 

[sawfun9]

If an SDC isn't doing it try a BDC, it'll run then. Ha Ha Ha Ha

 

[67L36Driver]

And, make shure the impulse passage is clear and your new gasket isn't blocking it.

 

[saxman]

I will check thus stuff. Thanks guys

 

[rmh3481]

+1 on the gasket covering the pulse passage.

Varnish can easily plug the screen and internal passages. Do you have or know anyone local that has a sonic cleaner? Otherwise use brake clean, its not as hard on the nozzle, check valves and related but will dissolve any varnish. Shoot a little in through where the adjustment jets thread in. Take the L/H jets out one at a time so you dont mix them up. You should be able to see the spray in the throttle bore and the metering chamber indicating that the passages are open.

Reassemble using the sdc schematic;
http://wem.walbro.com/distributors/ServiceManuals/SDCSeries.pdf

 

[redunshee]

It takes 10 seconds to pull that screen.

Yup. Gotta pull screen and look to see that passage is clear. If I use air its at a very low pressure. I typically don't however.

 

[heimannm]

Be sure to pressure test the carburetor before you install it to make sure everything is tight and seating properly. I have run across two or three that had leaks due to a warped cover and they would never work properly. I ended up replacing the stamped cover with a cast one that had the "crush rib" and all problems were solved.

Mark