Problem with Johnson QD 18

[blpierce76]

I have a 1957 johnson qd 18. I just got it and intalled a new water impeller and rebuilt the carb and put in new coils. I got it all back together and I can get it fire up. When its running at higher RPMs it runs great. However, at idle it runs for a bit and then starts to bump and cough.

I noticed at lower rpms the magneto plate/throttle vibrates back and forth quite a bit. Im thinking this is the problem, but Im not sure why its doing it. The only things i removed when replacing the coils was the retainer and support. Could I be missing something?

Thanks.

 

[racerone]

Re: Problem with Johnson QD 18

Coils must be properly positioned on the magplate.

 

[boobie]

Re: Problem with Johnson QD 18

The coils could be hitting the flywheel or you have a worn mag plate.

 

[HighTrim]

Re: Problem with Johnson QD 18

Need a little more definition on the cough. Is it a lean sneeze? Did you try tuning it out with the low speed needle? What were you initial settings? Will choking it slightly smooth it out?

Now if it is not a fuel related issue, you have to determine where the miss is coming from. Did you replace the plug wires? Any arcing? Try running in dark to see if you can see it arcing out anywhere. When you installed new coils, did you pull through the plug wire so that you can properly twist the coil onto the plug wire, or did you try to push the coil down onto the little nub of wire coming out of the mag plate? Are the coil laminations flush with the mounting boss of the mag plate? Points clean and gapped at 020?

Which plugs are you running? Are they sparking?

 

[blpierce76]

Re: Problem with Johnson QD 18

Need a little more definition on the cough. Is it a lean sneeze? Did you try tuning it out with the low speed needle? What were you initial settings? Will choking it slightly smooth it out?

Now if it is not a fuel related issue, you have to determine where the miss is coming from. Did you replace the plug wires? Any arcing? Try running in dark to see if you can see it arcing out anywhere. When you installed new coils, did you pull through the plug wire so that you can properly twist the coil onto the plug wire, or did you try to push the coil down onto the little nub of wire coming out of the mag plate? Are the coil laminations flush with the mounting boss of the mag plate? Points clean and gapped at 020?

Which plugs are you running? Are they sparking?

Well the motor bumps hard to one side then it "sneezes". It keeps doing that at idle until it eventually dies. I tried adjusting the needles and couldnt get it to stop. I started with 1 turn out on the low and 1 1/2 on the high.

Did not replace the plug wires, they look like they have been replaced recently, havent notice any arcing. I pulled the plug wire through to insert into the coil. I think the coils are flush, may have to check them again. Points are clean and I gapped them at 0.020. I'll probably recheck that tonight too.

Also, I notice a spring on the right side of the power head that is attached to the bottom, but the top came off. I dont recall removing it. Where does the top side of this spring attach?

 

[blpierce76]

Re: Problem with Johnson QD 18

Any ideas where that spring on the right side is supposed to connect

 

[HighTrim]

Re: Problem with Johnson QD 18

It pulls the plug wires down and in tight to the motor. Loop the other end around the wires.

 

[blpierce76]

Re: Problem with Johnson QD 18

OK so i loosened the coils an pushed them toward the center while i tighetened it down. No more bumping. Must have been hitting. Thanks for the advice. Motor runs like a champ now, but I have to replace the drive shaft seal on the lower unit now, and we should be ready to hit the water with it.
\
Thanks

 

[HighTrim]

Re: Problem with Johnson QD 18

Just so you know, when setting the coils, the edge of the laminates must be square with the mounting boss. If you don't have a coil locating ring, run your nail up the boss, if it catches on the laminate, the coil is too far out.

You don't want it too far in either, or your spark will be weak. It is amazing the difference in spark quality from minor movement of the coil.

 

[kfa4303]

Re: Problem with Johnson QD 18

Hi bl. These links may help.

http://forums.iboats.com/engine-fre...-change-coils-set-points-old-omcs-294072.html
Johnson
http://forums.iboats.com/johnson-evinrude-outboards/grandads-johnson-seahorse-10-a-506678-2.html