55HP Chrysler outboard backfiring no start HELP!

[CrakkBaby]

Hi guys new to this forum I have a 55 HP outboard motor that is a project I’m fixing for a buddy of mine. The motor sat for a couple years or so it didn’t do anything at first but I changed out battery lines and connectors, ignition parts and it turns over now starter motor engages to flywheel but when I try to start it turns over good but than just backfires really bad sounds like a gunshot, any help would be appreciated thanks. I suspect timing but honestly don’t know how to set first boat motor I worked on !

 

[racerone]

Check the flywheel key.-----Or perhaps switch plug leads.

 

[CrakkBaby]

How would you go about checking if those are in good condition and functioning properly? Thanks

 

[CrakkBaby]

So I just took my flywheel off and it seems the flywheel key broke off and part of it was melted to the flywheel or so it would appear .

 

[Texasmark]

There is your smoking gun. The flywheel key on any engine is critical to proper engine timing and even a partially sheared key can (and has for me) caused timing problems....backfiring...spark igniting the fuel mixture in the combustion chamber when an input port is open....be it an intake valve in a 4 stroker or open fuel/air inlet port in a 2 stroker.

 

[racerone]

Remove broken pieces from keyways.-----Lap the tapers.-----Clean the tapers.----Install proper key.------Assemble clean and dry.----Torque flywheel nut.

 

[fatlenny]

Torque flywheel nut is not a suggestion, It is a requirement. I thought I was good this last summer and then,,, I wasn't. Not a great time when you get out on the water, let off the throttle a mile off shore and your flywheel comes loose.

 

[Texasmark]

Torque spec for my 90 Merc was 150# as I recall. As others have said, it needs to be tight to protect the Woodruff key (engine timing). I don't know what your 55 spec is but I'd put at least 100# on it if it were mine, not knowing the exact value.