outboard problem

guys i have a 9.9 horse mercury that will not stay running when it is at idle,the motor will stay running at idle with the choke on but as soon you take it off the motor quits. it also wont stay running at a slow trolling speed it will for about 3 seconds then putt right out. any help would be great.

One of the first thing i do when getting a new motor is buy the work manual. They are like 35$ and worth every penny.

Like pgh said check the fuel line first thats easy. Also check the spark plugs for condition, connection to the wire, spark plug gap, wire to the coil. All very easy things to check.

Next check compression, you might be low on one or both cylinders, hopefully you do not have a cracked reed (i doubt but maybe) at this stage i would not check that, last resort would i do a test to check that.

If that does not fix it, get a carb rebuild kit. With basics tool, and a little thinking (help with a manual) you can rebuild the carb. The manual will have you reset the carb to factory setting so you will have a great point to start when tuning it in.

If that did not work, it would be time for a link-n-synk. This would involve putting all the adjustments back to factory (carb, adjustable timing, shifting) I have done this before to a 90hp tower of power 6cylinder, it seems daunting but really isnt bad at all. i had my manual to walk me through it. You will need a timing light, bought or borrowed, this helped me out a ton with my motor. Because the timing could be advanced a little tomuch to keep idle.

PM me if you need more help.

Sounds like a carb problem.  You can go over to www
iboats.com and they have dirctions on how to shock the carb system with seafoam.
Had an old 64 Johnson that had the same problem.  Did as they said and it works fine now, didn't have to take the carb off and do a rebuild.

The fact that it runs with the choke on eliminate compression and spark as the problem. I would agree with the post that suggest it is the carbs idle circuit.

I had a similar problem with a Johnson and removed and disassembled the carb and soaked it for 20 minutes in the 1 gallon Gunk can you can buy at Auto Zone for $20.00.

After 30 minutes it is clean and strips away all varnish and carbon etc. It ran perfectly when I was done.

ORIGINAL: 3006savage

The fact that it runs with the choke on eliminate compression and spark as the problem. I would agree with the post that suggest it is the carbs idle circuit.

Can definitely eliminate spark, but not compression. I can tell you this from too much personal experience...

His problem is most likely carb related...

Your "first step"? - depends on you!

Do you want it fixed for you or do you want to fix it yourself?
...if you want it fixed for you, take it to an outboard shop!

...if you have a few mechanical skills and want to do it yourself, buy a service manual and a gasket kit, spend an evening doing some reading, then the next evening do some disassembly and cleaning!

Outboard carbs. aren't really the "Genie in a bottle" to be feared as lots of people think...ALSO, there usually isn't a quick fix to solve their ills.

Out of curiosity, how old is this outboard?

Motor that runs with the choke on but not off is most likeley sucking air somewhere replace ALL hoses.

fuel restricted clean carb rr any bad hoses

Thing is that when a fuel line starts to deteriorate, it does from the inside thus small particles entering the fuel system and putting you back to where you started. A dirty carb.