50hp 3cyl not firing

[wynmill]

hi new to this forum
i have a 50hp 3cyl mercury outboard we have sparks on all cyl but it will not fire up we get a back fire through the exhaust with smoke but it will not fire up can anybody help
......phil

 

[Bondo]

Ayuh,.... Is it gettin' any gas,..??

Backfirin' would lead me to check the Timin',...

 

[gm280]

If it has gas/oil (whatever it takes) and air, and spark and correct timing, it has to start. So something is missing. All you have to do is figure out which one or ones of these are not there... Can you squirt some 50:1 fuel mixture into the carb(s) to fire it up? If so, your problem is a fuel delivery issue. If not, timing would be my concern. It squirting fuel/oil into the carb(s) fires up, check the carb(s) the fuel pump and hoses from the tank.... JMHO!

 

[enginepower]

A lean condition can cause backfiring as well. Squirt some premix as suggested to see if it starts. If not, you need to do a compression test. If all is good there, you need to verify your ignition system. Checking for spark that can jump a 3/8" gap and verify the timing is correct.