9.9 mercury problems

[sktruth]

I have an old 9.9 merc where i have to add oil to the gas. I always forget 2 or 4 stroke sorry. Everything was running fine, then... it just slows down and sounds like it sputters. i was maybe thinking fuel filter or fuel pump (if it has one). At wide open throttle it will go ok then slow way down and start sputtering. Any suggestions?

thank you in advance for your responses. tight lines

[GeordyBass]

It will be the fuel pump.... but try to change the filter as well and also get the carb rebuilt just for safety, maybe your injecters can be clogged as well.... good luck!

[Kevman]

If you have to add oil to your gas, your motor is a 2-stroke. 4-strokes use straight gas.

If your 9.9 Merc is old, your motor doesn't have fuel injectors, it has a carburetor. Come to think of it, I don't know of any fuel injected 9.9s, but I could be wrong.

Possible Causes of Sputtering:

1. Fuel pump bad (not pumping enough gas or leaking air in)
2. Air leak in fuel system elsewhere (fuel line internal or external)
3. Dirty carburetor (passages clogged)
4. Coil breaking over (assuming your motor has coils)
5. Points out of adjustment
6. Timing out of adjustment
7. Spark plugs fouled or gapped wrong
8. Fuel filter clogged--can be one under the cowling, or one in the pickup of the fuel tank.
9. Fuel tank vent not opened!

If you post the model # and serial # of your motor and a picture of the exterior, I can probably tell you what year it is. This info is usually found on a small metal tag riveted or glued to the exterior.

Things to try:

1. When the motor starts to sputter, pump your fuel bulb. If the motor picks up speed and runs better, you have a fuel delivery problem--likely a bad fuel pump or air leak in your main fuel line from the tank or the internal fuel hoses under the cowling.

2. Take your carburetor apart completely and soak overnight in carb cleaner, then blow out all small passages with compressed air, then reassemble. (non-mechanics should pay a shop to do this) If your motor hasn't had proper maintenance recently, you want to ask for a "Carb cleaning and rebuild kit installed." You will get a new float and other good stuff.

3. If the motor only starts to sputter when the motor is hot (i.e., been running for some time), then you may have a cracked coil. You can visually inspect the coils if you know where to look. They are round cylinders usually coated with blue or green epoxy. They are part of the ignition system. You can often see the cracks on the exterior.

4. If you don't know what year motor you have, points and timing will be hard to adjust correctly.

5. It's easy to pull your spark plugs and check to see if they are fouled. Covered with a lot of dry black ash is bad, as is covered with thick oily residue. Best is a nice clean surface with a tannish tint.

If you respond with more info on your motor, I can probably help you more. However, if you lack basic mechanical knowledge of outboards and do not have a service manual for your motor, I would strongly recommend you take it to a shop for diagnosis and repair.

Older outboards can run great but the points, timing, spark plug gap, carburetor, etc. all must be in good adjustment if you want the motor to purr.

Good Luck,
Kev

[GeordyBass]

If you have to add oil to your gas, your motor is a 2-stroke. 4-strokes use straight gas.

If your 9.9 Merc is old, your motor doesn't have fuel injectors, it has a carburetor. Come to think of it, I don't know of any fuel injected 9.9s, but I could be wrong.

Possible Causes of Sputtering:

1. Fuel pump bad (not pumping enough gas or leaking air in)
2. Air leak in fuel system elsewhere (fuel line internal or external)
3. Dirty carburetor (passages clogged)

Sounds exactly like the problem,,,lol,,,



4. Coil breaking over (assuming your motor has coils)
They do have coils, 1 for each cylinder.


5. Points out of adjustment
6. Timing out of adjustment

Timing and points more likely cause the idle to be really rough.




7. Spark plugs fouled or gapped wrong
8. Fuel filter clogged--can be one under the cowling, or one in the pickup of the fuel tank.
9. Fuel tank vent not opened!

If you post the model # and serial # of your motor and a picture of the exterior, I can probably tell you what year it is. This info is usually found on a small metal tag riveted or glued to the exterior.

Things to try:

1. When the motor starts to sputter, pump your fuel bulb. If the motor picks up speed and runs better, you have a fuel delivery problem--likely a bad fuel pump or air leak in your main fuel line from the tank or the internal fuel hoses under the cowling.

2. Take your carburetor apart completely and soak in overnight in carb cleaner, then blow out all small passages with compressed air, then reassemble. (non-mechanics should pay a shop to do this) If your motor hasn't had proper maintenance recently, you want to ask for a "Carb cleaning and rebuild kit installed." You will get a new float and other good stuff.

You'd be better off taking it to a mechanic,as carbs have to really be acid bathed.



3. If the motor only starts to sputter when the motor is hot (i.e., been running for some time), then you may have a cracked coil. You can visually inspect the coils if you know where to look. They are round cylinders usually coated with blue or green epoxy. They are part of the ignition system. You can often see the cracks on the exterior.

4. If you don't know what year motor you have, points and timing will be hard to adjust correctly.

5. It's easy to pull your spark plugs and check to see if they are fouled. Covered with a lot of dry black ash is bad, as is covered with thick oily residue. Best is a nice clean surface with a tannish tint.

If you respond with more info on your motor, I can probably help you more. However, if you lack basic mechanical knowledge of outboards and do not have a service manual for your motor, I would strongly recommend you take it to a shop for diagnosis and repair.

Older outboards can run great but the points, timing, spark plug gap, carburetor, etc. all must be in good adjustment if you want the motor to purr.

Good Luck,
Kev

[sktruth]

Thank you very much for the input. The serial number is OB212752. I don't know the model number or the year it was built. I will try to get some pics up soon of the engine. Thanks again for all the help.

[Fastfish]

The S/N beginning in 0B is going to be from the earely 90's the carb can be soaked in Power-Tune of course disassembled first but thats about the strongest cleaner available nowadays with a good cleaning a freshened up fuel pump you should have great running little motor providing you've got good compression and a healthy ignition system.

Fastfish

[Kevman]

That looks like a late 1987 model. 2-cylinders.

http://stores.shop.ebay.com/Outboardnuts/Mercury-Year-Lookup.html_

http://www.storesonline.com/site/573683/page/609739

The leading zero doesn't count.

If you can find the Mercury Service manual for it (I wouldn't recommend aftermarket manuals such as Clymer or Seloc), then you're in business.

Good Luck!
Kev