25hp johnson backfireing

[sambrigman]

Motor will not start, but it is back firing thru the the prop. What could cause this? Any advise greatly appreciated, thanks

 

[flyingscott]

Were the spark plug wires taken off at any time and reversed. Did you hit anything and shear the flywheel key.

 

[sambrigman]

No I did not hit anything, and the 2 cylinders wires are to short to cross?

 

[ondarvr]

Check the flywheel key, they do occasionly shear for no apparent reason.

 

[flyingscott]

agree pull the flywheel anyways

 

[sambrigman]

could a sheered key cause the motor to loose fire

 

[flyingscott]

You haven't lost fire the backfiring tells you that. You just have fire just at the wrong time the fly wheel key can cause that. Unless there is something more happening.

 

[racerone]

There are about 4 distinc different models of 25 hp motors.--You have NOT posted a model number.---But if there are orange wires going to the coils the blue stripe goes to the top one.-----Is this something that started suddenly ???---And backfiring is a classic symptom of plug wires reversed !!!