'74 15hp evinrude

[johnnybahama]

Just completed replacing entire ignition and shimming armature. 120psi up and down. carb clear and low speed set.
Problem is mid range. Idles great, but when you roll it on it runs rough, then the power snaps on and runs great.
It's getting from low speed to high speed. I can back off a bit and speed up fine. Any help? Thanks Jon

 

[Chriswalden]

Re: '74 15hp evinrude

Sounds to me like you have a carb timing issue. I just fixed the same problem on my 1980 Johnson 9.9. The throttle plate cam has the touch the carb arm at the timing mark located on the throttle plate cam. For more information on how to adjust this, google Leroy's ramblings and click on Johnson/evinrude 9.9/15hp Carb/fuel pump repairs and scroll on down about half way.

 

[johnnybahama]

Re: '74 15hp evinrude

Throttle cam is right on the arrow. I am at a loss.

 

[jmendoza]

Re: '74 15hp evinrude

Hook up a timing light to top cylinder spark plug wire, you will need a 12 volt battery to power your timing light. Look for the mark on the flywheel to fall within the wide mark on the stator. Repeat for the bottom cylinder. The flywheel mark should stay within the width of the large mark on the stator at all RPMs and throttle positions. One thing to remember is that although the timing changes relative to the crankshaft angle, because the stator moves as you open and close the throttle, the timing in relationship to it does not change.

 

[johnnybahama]

Re: '74 15hp evinrude

I set the points to open at the start of the wide mark on the armature plate. Should I have set them in the middle?
I used a battery powered timing light ,but couldn't see the mark very well, sunlight.

 

[jmendoza]

Re: '74 15hp evinrude

Timing sounds right to me. You can also check it running as I described above, if you have a strobe type timing light.

It could well be your carb has debris in the low speed pocket, and that could be the problem, but first, do a fuel pump test: Plug in the fuel line from the tank, squeeze the primer bulb until it's hard, then remove the fuel line off the carb and see if it spurts gas when you pull the rope, if it does, the pump is good.

To properly clean the carb, remove it, get a rebuild kit, and clean the carb, being sure to remove the welch plug and blow out the low speed mixing chamber real good. Replace the low speed needle packing too, a new one comes with the rebuild kit. Put in the new welch plug with gasoline proof sealer, and tap it in with a 1/4" diameter rod.

 

[johnnybahama]

Re: '74 15hp evinrude

Went through the carb and the only thing I found was the needle bushing was missing. I also replaced the packing gland. I'm thinking that it may be too much fuel on the high speed end. Idles fine , but when you get passed off idle it starts to bog. It stays there for a few seconds then the power snaps up, running good. I wondering if someone changed the main in the past? Also, no thermostat. Ran it for 30 minutes tinkering and it was cold, even the sparkplug bases. The reed valve housing was actually accumulating condensation.

 

[kbait]

Re: '74 15hp evinrude

Those point motors really don't like running too cool. Install thermostat, give it a decarb, new plugs and try it again.

 

[OptsyEagle]

Re: '74 15hp evinrude

Are you absolutely sure that there was no needle bushing in it before. When inserted, they are almost impossible to see. It's difficult for me to understand why someone would remove it and not put another one back in and I doubt it would work all that well without it. I also am pretty sure you would have some kind of problem if you now have 2 of them in there.

Just a thought.

 

[johnnybahama]

Re: '74 15hp evinrude

Well Gentlemen since my last post a bit of PFM has occured. I called my friend about the motor and all seems good, He said it starts every morning on the first pull and spools right on up to get on plane. I dont understand, but will ask no questions. I still plan on going over and installing the thermostat and leave it alone. Maybe it just needed a little training to get back in shape! Anyway thank you all for your advice. Until next time, All the Best, Jon