66 Johnson 18 Hp carb problems

[flintcreek]

I am stumped on this one. 66 model fd-19 18 hp has new coils, points,condenser and plugs and wires. Jumps fire 1/2" on tester and compression is 120 on both cylinders. I have cleaned the carb.

Now for what it is doing. It does not run at WOT. Took it out this morning and it Idols fine, would not open and run at WOT. So I screwed the idol screw all the way in and it started to open on up and run at WOT. Packing around the idol screw seemed loose so I took it home and put in new o-rings where the old packing was, took it back out this afternoon and it would not open up and run, even if I screwed the idol screw all the way in. Any ideals.



Thanks,
Flintcreek

 

[F_R]

Re: 66 Johnson 18 Hp carb problems

The idle screw really has little if anything to do with high speed operation. Your trouble is elsewhere. Did you check the high speed orifice in the bottom of the carburetor?

 

[flintcreek]

Re: 66 Johnson 18 Hp carb problems

Shot carb cleaner through the high speed jet and blew it out with air. Should I try to take it out of the carb? My eye sight has I started going and I could not see it in the hole very good.

Thanks,
Flintcreek

 

[flintcreek]

Re: 66 Johnson 18 Hp carb problems

Went down to the shop and ground down a screwdriver to fit the high speed jet and backed it out. The jet was clean as could be. I'm lost....Flintcreek

 

[Brokeback Johnson]

Re: 66 Johnson 18 Hp carb problems

Could be that the gasket that seals the bowl to the high speed nozzle is not sealing. #57 in this diagram. If this does not seal there will be a rich condition that won't let the engine rev......seen this one several times now.

http://www.boats.net/parts/search/BRP/JOHNSON/1968/FD-22A 1968/CARBURETOR GROUP/parts.html

 

[flintcreek]

Re: 66 Johnson 18 Hp carb problems

Thanks, is that gasket supposed to be just like a o-ring or a gasket that is round on the outside with a cut out some thing similar to a cross shape, not round? Maybe I have been using the wrong gasket in this spot. Since it is Sunday it may be tomorrow after work before I can check it out.

Thanks,
Flintcreek

 

[flintcreek]

Re: 66 Johnson 18 Hp carb problems

Replaced the gasket on the high speed pick between the top and bottom halves of the carb still does not want to run right....Flintcreek.

 

[flintcreek]

Re: 66 Johnson 18 Hp carb problems

Carried the motor over to a mechanic that works on these old Johnson's all of the time. He noticed the linkage from the carb to the timing cam was homemade, and he thought the wrong length, he believes this is the problem. So he thought he should be able to find the correct one, but he was under the weather so he said it would probably be Monday before he tackled it.

Flintcreek

 

[flintcreek]

Re: 66 Johnson 18 Hp carb problems

Well got the motor back from the shop Monday and carried it out this afternoon. Ran good, just like it should. Mechanic changed the linkage between the carb and cam, (with the wrong length rod, it would not link and sinc) and new gasket on the center part of the high speed jet like Brokeback said....It appears I had several issues going on with this old motor, because I had already fixed a exhaust leak. Thanks for the advice....actually caught a few fish this afternoon. Now with this one fixed back to my 35 hp Johnson.

Thanks for the help.

Flintcreek