Motor starting hard when warmed up?

[Chode2235]

Towards the end of last season my motor started acting up a bit.

It is a Yamaha 150 2 stroke (carbed), and after it starts up (little cold blooded) it fires up instantly the rest of the day, unless you turn it off for a couple hours or so.

When you do that it will turn over and stall out right away, and then it can't be started unless choked and revved up a bit (like cold starting procedure). Once it starts this way it doesn't seem to be firing all that well and sputters and sneezes a bit. Most of the time this works itself out when I run it a bit, but a couple times it was never "right" the rest of the day and would stall or sputter badly when I came off plane.

I'm thinking carbs or fuel pump ... ?

Figured I would ask the experts.

[marine_man]

Do you pump your primer bulb prior to the cold start, vs not during the "warm" restart?

I'm wondering if there's not a pin hole in one of your fuel lines, allowing the gas to drain back to the tank...

marine_man

[Chode2235]

I have done both, as I originally thought that the fuel pump wasn't keeping a prime. But it is pretty/mostly full when I pump it (half to 3/4) after running.

Same thing happens when I pump it up and try to start it.

[CAMAN]

It almost sounds like one of the cylinders is flooding or you have a bad/dirty sparkplug or both.

I'd check all the plugs first and replace them if they are a couple years old.

[Chode2235]

Yeah, I'll replace the spark plugs this spring, and probably run a concentrated batch of sea foam through there to decarb and clean out the fuel line.

[20lbSloughShark]

Turn the motor to the side and squeeze the primer bulb. If it squirts gas everywhere its a $4 fix. The o ring in the connector to the motor goes bad.

[boatfixer]

Are you saying that there is a definite difference between the 1st initial Cold start and a Cold start after sitting for an hour or 2? And that you have step by step, repeated the initial Cold start and still won't start and run right?

I would want to do a compression test both Cold and warm as well as a spark test both Cold and warm. This would rule out both of those.