1980 evinrude 35 hp backfiring problem

[hawkeye]

I have a 1980 evinrude 35. starts up ok, then backfires continually from 1/4 throttle to full. changed the plugs, good gas, motor in good shape. any ideas?

 

[joereeves]

Re: 1980 evinrude 35 backfiring problem

Actual backfire..... like a shotgun firing out the exhaust? = Sheared flywheel key, faulty plug wires (cross firing), powerpack diode shorted (ck ohms white wire to black/yellow wire) should read one way only.

Or like a mild backfire..... engine spitting back thru the carburetor? Carb adjusted too lean, carburetor fouled, throttle butterflies opening too soon.