Fd-21 1967 20hp won't idle

[grizzrider09]

I have been working on this motor for a while now. The compression is 85 on top and 84 on bottom. I have replaced the coils and have great spark. I have cleaned the carb three times now and it will crank every pull but won't idle. It will run if you crank in gear and gas on it. After I cleaned and rebuilt the carb I'm not sure if I have the top needle in correctly. There are threads on the needle and a sort of bushing that threads on there. What I'm not sure of is this bushing is supposed to be threaded closer to the needle point or the nut that holds the needle in place. I'm out of ideas and I will post pics tomorrow if needed and if anybody has pics that can help me it would be much appreciated. Thanks

 

[lindy46]

Re: Fd-21 1967 20hp won't idle

The barrel that the needle threads into must be tightened by the packing nut. If the needle can't be adjusted, the barrel is just spinning in the opening. Once you get everything tightened down properly, seat the needle and then open it 1.5 turns to start.

When you cleaned the carb, did you remove the welch plug on top of the carb and clean the idle circuit beneath? A dirty idle circuit is the most common cause of poor idle.

 

[bbstacker1]

Re: Fd-21 1967 20hp won't idle

If the compression you got is correct that could be affecting your idle also. Those motors should be around 100 as a minimum, most I have tested run from 100 to 125. But as lindy said make sure your low speed idle circuit is clean and then tightened down properly, also check your needle to make sure the tip area is not damaged.

 

[kfa4303]

Re: Fd-21 1967 20hp won't idle

Hi grizz. For starters, if you have an FD-21, then you would actually have an 18hp and it would be a '65 model. The 20hp was first made in '66, so you probably have an '67, FD-23, 20hp. Thankfully, they're virtually identical to the 18hp. Sounds like you need to get you carb dialed in a bit. As. Lindy46 pointed out, the needle(s) should pass through the threaded nut, which should be threaded in just enough for it to apply a bit of friction to the lo speed needle, but not so tight that the needle can't be adjusted. Here's a great link that can walk you through the job.

Maintaining Johnson E & FD Serie

 

[grizzrider09]

Re: Fd-21 1967 20hp won't idle

I didn't clean the welch plug so that may be my problem. But I'm not sure that I understand yet on the needle. Do I put the barrel in and tighten the packing nut then thread the needle in till it seats or thread the barrel onto the needle, push it in till it seats then tighten the packing nut? Sorry for the dumb question but this is my first johnson

 

[lindy46]

Re: Fd-21 1967 20hp won't idle

Put the barrel in first, then add packing. Put on the nut loosely, then start the needle. Tighten the packing nut enough so the needle doesn't spin with the barrel, and seat the needle - it should be pretty snug so it doesn't turn when the motor is running. I usually tighten it so you can't turn the needle unless the knob is attached. Then back out the needle 1.5 turns.

 

[kfa4303]

Re: Fd-21 1967 20hp won't idle

Hi grizz. Here's a great little link that can walk you through the carb rebuild. It's for a slightly different model, but all of the steps are the same.

5.5 HP Evinrude Johnson 1954-1954 Carburetor Tune-Up Procedure

 

[grizzrider09]

Re: Fd-21 1967 20hp won't idle

Hey guys just wanted to say thanks. I finally got home and able to fool around with this motor and got her to idle. I think I may have a damaged seat though cause its still coughing and i have spent over an hour adjusting the idle needle. She will either not crank if the Idle needle is not backed out to 1 1/2 turns or wont run smooth at 1 1/2 turns. After I put her in gear and give it a little gas it spits and sputters and you make one little turn on that needle it will take off like a rocket but let off and she goes dead cause it spits and sputters so when it idles. Im going to order another carb kit and replace everything this time and see if she does better.