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my 8270 was running fine until I spent a few days working on the self propel. Now it is running but revs up and down and never clears up. It acts like it's starving fuel but I rebuilt the carb, new fuel filter and lines recently. Today I took off the carb and made sure everything is clean. Could it be the ignition coil and if so how can I diagnose it?
Thanks

A ignition coil well not make it run the "revs up and down". check the carb for over rich and check the governor.

When you rebuilt the carb, did you replace the float needle and seat? Also, did you clean the idle jet on the side of the carb?

I did replace the needle valve and seat. Is the idle jet the screw adj. they call the alt. adj? If so I didn't but will do so tomorrow. Thanks

When you replaced the float needle and seat, make sure you reset the float level. The idle jet is on the left side of the carb, many times covered by a decal. Many times the center hole will be plugged. It is very small and tough to clean if plugged.

If Rivets will agree...reset float means the float must control the inlet needle or you will starve or flood (gas). In the old days the dimensions were given in the owners manual, usually in fraction inches or decimal inches measured from the carb cover. Fairly easily set by bending a metal "tang" on the float. (Corrections eagerly welcomed from mower specific engine gurus)

Moto, you are correct. I adjust my floats so that the is a slight downward angle on the float. The float pin side of the carb is SLIGHTLY higher, when the carb is tipped upside down.

I don't consider myself a mechanic and I have done what my abilities allow. I removed the carb again,cleaned the orifices,changed the float and set the height at7/16" per the service manual. Set the altitude setting at 1/2 turn from seat. Now I prime and it starts and runs a few seconds and quits. Prime again and after 5 to 6 pulls starts and runs a few seconds. I'm at a loss, especially since it was running fine before I worked on the self propel.
Thanks for listening!

Don't look now , but you are slowly becoming a mechanic:laughing: Carbs need really clean handling. The holes are easily plugged. Try again on the orifices by blowing thru them . If you don't have an air compressor use a bicycle pump.

Well I went through the carb again with no success. I have another old carb and put it on. Started and ran fine until I turned it off. Didn't want to restart but after many pulls, it did. Seems like it is either flooding or the bowl is slow filling. It does this every time I turn it off. Guess I'll try some more tomorrow.

I have run across the same thing and it was bad gas but that would be to easy a deteriorating fuel line would do it too

Thanks but the fuel lines are new and I only use ethanol free gas. But then who knows what the previous owner did!