Logo
FULL SITE MENU

Johnson 6hp (model CD-23E)

D

Dan Heerts

New member
Hey guys. I have an old 1966 6hp Johnson outboard motor. This little engine has ALWAYS run like a champ. Starts on first or second pull and doesn't skip a beat. I recently had it "freshened up" as it was acting "funny. I put new plugs in, had the carb taken apart and completely rebuilt, new fuel pump, new water pump. Etc.

Here is the problem. Once the engine is up to normal operating "Temps" it will NOT operate at full WOT. Like it'll run a low to medium speed, but won't get up and GO at full throttle. It's like it's in "LIMP" mode almost.

Anyway, Not sure what to look at. It's getting fuel, as it will still start on first or second pull and run just fine until it's warmed up.

Any help or input would be great. Thanks
 
Check compressions. What figures do you get ?

Inspect / clean / reset or replace points

Inspect coils

Check its is firing on both cylinders and check for two good sparks. How large an air gap will they jump?
 
Vics,

thanks for the reply. I am checking compression today. Also going to inspect the points, condensors and coils. I know they are the only thing left that is original to the engine, so they are OLD. IT's probably time to change points, condensors and coils no matter what.
 
Lack of high speed power like that is almost always running on one cylinder. Yes, they will idle just fine on one. However, you relate it to temperature. But still, I predict it is an ignition problem. Coils will do that.
 
Right. Gotta be the coils. For SURE they are cracked and arcing out to the stator plate underneath.......if they are really the originals. The original coils were made of a different material that with age certainly are cracked. The o-ring at the bottom of the float bowl is also critical. If it does not seal properly the motor will run rich, that will cause a problem as well. However, if the carb was property rebuilt that will come included in the overhaul kit.
 
Thanks guys. I have new coils, points and condensors on order already. I figure they need to be replaced no matter what. I did just run a compression test on each cylinder. Now, I just have a cheap harbor freight model, so I never really rely on the PSI it tells, me just if cylinders are matching or close. I installed (screw in) pressure gauge, and pulled over the engine a half dozen times. On BOTH cylinders I get a reading of exactly 55 psi. Both are identical. It also HOLDS that PSI, so no leak down passed the pistons/rings.
 
Last edited:
Timguy...I rebuilt the carb myself, I do them on my atv's, sleds, dirtbikes, etc. I have an ultrasonic cleaner as well. I took the carb completely apart, ultrasonically cleaned it and rebuilt it top to bottom with all new parts. So the O-ring in the bowl was replaced as well.
 
55 psi is low, but since it starts easy and idles, I'd say it actually is better than that. There likely is a considerable pressure drop across the check valve in that gauge
 
Last edited:
Back
Top