1998 Yamaha 50 4 stroke not starting

[AKriderK9]

So, have a 1998 Yamaha 50 hp 4 stroke. It ran great once….. went to start it, and it took over an hour to get it to run. Now, I can only get it to pop. Here’s the rundown of all I’ve checked…..

Compression is good, all cylinders within 2 psi of each other.

Rebuilt carbs

Replaced all fuel lines

New fuel pump

New plugs

New starter/solenoid

Now, I have checked spark, I have compression, and I have fuel. This is the electric choke model and it’s also a remote controlled unit (not a tiller). I am at a loss, what do I check next? Never seen something that wouldn’t start with fuel, spark, and Compression. Added a photo of the carb setup for reference. Thanks in advance! Almost at my Witt’s end!

 

[AKriderK9]

Also, like I said, it will pop, but won’t fire, kinda just coughs, but does not run. Just figured I’d clarify what I meant by “it pops”

 

[racerone]

Checked flywheel key ?----How did it run for you last season ?

 

[99yam40]

put a timing light on it to see if spark is happening at correct time/
what was the compression readings?

 

[AKriderK9]

What am I checking on the flywheel key? Isn’t that in a slot on the crank shaft? I checked timing after fighting for an hour to get it started. At idle, spark was sitting at 5°.

 

[AKriderK9]

Compression was right around 130 cold, according to Yamaha anything over 122 cold is fine

 

[mike_i]

Do you have a kill switch? Even though you say the motor pops most likely it wouldn't be a kill switch problem, I'm grasping at ideas for you. Have you confirmed the carb bowls have fuel in them? Have you tried giving it a shot of starting fluid?

 

[99yam40]

Compression was right around 130 cold, according to Yamaha anything over 122 cold is fine

are you sure the 4 strokes have that compression ?
I thought they were higher then the 2 stroke motors

good compression, good spark at the correct time, and proper fuel to air ratio is needed.
too much fuel or not enough could be your problem.
Are the plugs wet when you pull them after trying to start?
if so maybe the problem is too much fuel to air

Do you open the throttle some before trying to start using the choke?

 

[AKriderK9]

Well, racerone set me on the right path! Broken flywheel key that had my motor 75° retarded. New key and she fired right up. Ran great! I just got the motor a few weeks ago, so I had only ran it once before all this. I will need to play with pitching now, it’s on an 19’ fiberglass boat and was topping out around 16 mph, but it’s running an 11 pitch, 11 3/8” prop. Any suggestion for the correct prop for the T50?