'74 Evinrude 9.9 Issue

ryan261

Cadet
Joined
Sep 13, 2024
Messages
8
Hello, My father had an old ‘74 evinrude 9.9 laying around in the garage for about 20 years and my son and I decided to get running again. We have spent the last 2 months on and off working on it and even repainted it. Looks brand new once again. We got it running really well on a stand so the other day we took it to our stock pond to test it out. At full throttle, it only seemed to run on one cylinder. But, if I adjusted the low speed adjustment valve to really lean, it would rev up and take off. But, as soon as I came down on the throttle it wouldn’t idle and would die. It would be hard to start back up unless I turned the low speed adjustment more rich. In the beginning, we did a compression test and check for spark, replace the ignition coils, and added a carb kit and all that. Does this seem like maybe a fuel delivery problem? I’m skeptical of the fuel line hose and the bulb that we have, it seems kind of cheap. My next thought was to possibly go to a little bit larger diameter, fuel line hose and replace the bulb with a better quality one. Just confused as to why I have to run it so lean in order to get it to run as it should at full throttle.
Any help with this would be greatly appreciated, my son is itching to take this thing out for an adventure!
 

jimmbo

Supreme Mariner
Joined
May 24, 2004
Messages
13,446
Do You have a Spark that can consistently jump a 5/16" gap on both Plugs?
Did you replace/clean and set the Points, to 0.020"?
 

ryan261

Cadet
Joined
Sep 13, 2024
Messages
8
Just a quick follow up, I removed the slow speed adjustment needle and found that the little nylon bearing was brittle and broken into small pieces. I used a small wire to loosen them and tapped the carburetor so they would all fall out. I am getting another nylon bearing to replace it.
Could that have caused the problems we have had with motor not wanting to run at full throttle?
Do You have a Spark that can consistently jump a 5/16" gap on both Plugs?
Did you replace/clean and set the Points, to 0.020"?
I have not yet looked at the points but that is probably next on the list. I recently found a problem with the nylon bearing for slow speed adjustment. See my follow up post.....
 

ryan261

Cadet
Joined
Sep 13, 2024
Messages
8
@ 60lbs ID say it's done or head gasket.

Others might say it's "ok" not sure on this one.
Yeah I have read others who have had similar numbers, but still ran strong. We did replace the head gasket as well, the original one was actually in decent shape.
 

saltchuckmatt

Commander
Joined
Jul 19, 2019
Messages
2,646
End play ...side to side movement of the piston moving it with your finger.

If it moves a strong eighth.....it will need honing and rings.
 

racerone

Supreme Mariner
Joined
Dec 28, 2013
Messages
37,827
??---A strong 1/8" could really not happen.----Motor would have quit long before that.---The cylinder head was warped.----Did you refinish it before installing the new head gasket?
 

ryan261

Cadet
Joined
Sep 13, 2024
Messages
8
practically no movement of the pistons. I’m getting the new carb kit tomorrow and will be installing the new nylon bearing for the slow speed needle, we’ll see how it behaves after that. If that doesn’t fix it, then I’m going to the ignition points next.
 

airshot

Vice Admiral
Joined
Jul 22, 2008
Messages
5,084
Never run an outboard wide open in a test tank, wait for on the water to test wot. Many times the compression will come up after running if it has set for years. All carb adjustments should be made in the water whole underway in the water. Test tanks are for testing and making rough adjustments. You should pick up a factory service manual for your motor to get all the settings you need. No aftermarket, find a real OMC manual.
 

ryan261

Cadet
Joined
Sep 13, 2024
Messages
8
Got it. We have been testing the motor on a jon a boat in our stock pond. And have been trying to make adjustments on the water. We can get it to run at WOT, but the low speed adjustment needle has to be set very lean, when you come off the throttle though, it just dies.
 
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