1976 Johnson 20hp poor idle

[AEROCOOK]

My 76 Johnson 20hp aquired a poor idle this summer, and I am looking for tips on things to check. To begin with, let me fill you in with some possibly relevant info...
Half way through the summer the pick up coil was replaced because the motor suddenly died and I diagnosed no spark. After I replaced the coil the idle problem surfaced and I found that the only way I could get the motor to idle at all was with the slow speed needle 3 and a half turns out. Even at this setting (which I think is extreme??) the idle is inconsistant. I have cleaned the carb twice with no improvement. I noticed quite a bit of play in the throttle linkage allowing at least half an inch of back and forth movement in the plate, is this normal? Are reeds a common failure on these motors?

 

[JUSTINTIME]

Re: 1976 Johnson 20hp poor idle

your idle needle could be worn
i would order a carb re-build kit
when u pull the carbs u can look at the reeds
new spark plugs
new fuel filter

 

[AEROCOOK]

Re: 1976 Johnson 20hp poor idle

your idle needle could be worn
i would order a carb re-build kit
when u pull the carbs u can look at the reeds
new spark plugs
new fuel filter

Thanks for the response. The plugs were replaced with no improvment, I will replace filter. Correct me if Im wrong, but wouldnt a worn needle have to be screwed in further to make up for the wear?

 

[JUSTINTIME]

Re: 1976 Johnson 20hp poor idle

not always
could be needle sticking

 

[F_R]

Re: 1976 Johnson 20hp poor idle

Are you sure you have a 1976 20hp? They show a 15, 25, and 35hp for that year.

Anyhoo, if it is similar to one of the above, there is a plastic seal called a "bearing" around the slow speed needle, way down in the hole. You can't see it, but it's in there (if it's a 1976) If it is worn it allows air to get in, upsetting the mixture. Note: this is not referring to the plastic friction retainer that you can see right where the needle goes in. The bearing is down in there somewhat and is part number 314166 and should be included with a carb kit.

 

[BoatBuoy]

Re: 1976 Johnson 20hp poor idle

To get the bearing out that F_R mentioned, get a long, keen, dry-wall screw. Screw it into the bearing a turn or two and pull straight out. To answer another of your questions, it is very uncommon for reeds to be bad.

 

[iwombat]

Re: 1976 Johnson 20hp poor idle

If the problem surfaced after the coil was replaced, I wonder if it may be a poorly seated plug wire at the coil. Did you do a spark check after replacing the coil?

 

[Xcusme]

Re: 1976 Johnson 20hp poor idle

He said ..."the pick up coil was replaced...." not an ignition coil....

 

[Boatist]

Re: 1976 Johnson 20hp poor idle

Really need to know what motor we are talking about as Johnson or Evinrude did not make a 20 hp form 1974 to at least 1990. 9.9, 15, 25, 35 yes. 20 HP NO.

 

[AEROCOOK]

Re: 1976 Johnson 20hp poor idle

I was waiting for someone to question the model and year... Its Canadian and the model number is 20BA76D.
Ever since I bought the motor Ive been told it doesnt exist! A number of marinas Ive dealt with have theories about it, like maybe its a commercial motor etc. etc.
Sounds like a carb rebuild is in order assuming I can get a carb kit for a motor that isnt listed.

 

[F_R]

Re: 1976 Johnson 20hp poor idle

Can you stand another theory? Maybe it is from Belgium, sold in the European market. Does it have a "B" ahead of the serial number?

 

[AEROCOOK]

Re: 1976 Johnson 20hp poor idle

Can you stand another theory? Maybe it is from Belgium, sold in the European market. Does it have a "B" ahead of the serial number?

You are not the first to suggest that theory, but the tag on the motor says "made in Canada" and oddly enough there is another identical motor on the same small lake where I do my boating here in Ontario. If I ever solve this little mystery I will submit a post to advise you all. Are there any markings on the carb it's self that would be beneficial in ordering the correct rebuild kit, or do you think a kit from a 25hp would be the same?

 

[F_R]

Re: 1976 Johnson 20hp poor idle

OK, failing on that theory, my second wild and irresponsible guess would be that it was made in Canada for export to some other country and for some unknown reason never left Canada. Maybe it's supposed to be running up and down the Amazon River or something. That advice is free and worth every penny.

 

[AEROCOOK]

Re: 1976 Johnson 20hp poor idle

OK, failing on that theory, my second wild and irresponsible guess would be that it was made in Canada for export to some other country and for some unknown reason never left Canada. Maybe it's supposed to be running up and down the Amazon River or something. That advice is free and worth every penny.

Thanks F R.. Ill take all the free advice I can get!!

 

[ezeke]

Re: 1976 Johnson 20hp poor idle

Try this link:
http://web.archive.org/web/20011214121112/http://www.evinrude.com/DockTalk/modref/jomodyr/JHP20.html

I also found the 1976 Model here without trouble:
http://skoterskroten.com/batmotorer/Listor/arsmodellstabell.pdf

Just use acrobat search and enter the model without the last letter.

 

[F_R]

Re: 1976 Johnson 20hp poor idle

:%Skoterskroten??? OK, I give up. What country is that? They have a lot of models listed that it would seem BRP never heard of.

 

[ezeke]

Re: 1976 Johnson 20hp poor idle

The first reference is from OMC's own archives.

For what it is worth BRP does not have a 1976 Johnson 115HP or 135HP listed either. I suppose some could argue that ergo, they did not exist either.

I believe that the 20HP and 25HP are essentially the same motor except for carburetion.

http://www.maxrules.com/graphics/ej_pdf/EJ_Pages_18_Thru_20.pdf

 

[jim_in_day]

Re: 1976 Johnson 20hp poor idle

"Really need to know what motor we are talking about as Johnson or Evinrude did not make a 20 hp form 1974 to at least 1990. 9.9, 15, 25, 35 yes. 20 HP NO."


I have a 1985 johnson 20hp, and it shows up on the BRP website. I do however agree that for 1976 the 20 doesn't show up as a US model, but having a Belgian made 4 hp johnny, I understand his frustration. Finding information about non US models is very frustrating. I can verify my motor, but not where to get a parts manual to order replacement parts.

 

[BoaterNut]

Re: 1976 Johnson 20hp poor idle

Is the gap "set-able" on your pick-up coil ?? It sounds like it might be a little wide, which wouldn't effect high speed operation as much as low speed. Only other thing I can think of is "wobble" in the crank if the engine has a lot of hours. Wobble would cause the gap to change at lower RPMs and give an erratic idle. When the engine revs up, the wobble goes away and everything would be fine. Don't make too many changes till you've corrected / verified that the installation of your pick-up coil is correct. That's when the problems started.

 

[Chinewalker]

Re: 1976 Johnson 20hp poor idle

The 20hp models were Canadian only. Lots of the northern lakes had 20hp limits. It was essentially the 25hp model... Differences in the piston dome, cylinder head and carburetion...
- Scott