56 FD-12 JOHNSON

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dusty221122

Cadet
Joined
Sep 27, 2005
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10
GOT A PROBLEM WITH THE THROTTLE HANDLE. HARD TO GET IT OPEN TO THE WOT SETTING. WHEN I HAVE IT IN NEUTRAL IT OPENS UP GREAT. WHEN I DO ROLL ON IT I CANT GET IT TO RUN WIDE OPEN UNLESS I PUMP MY THE PRIMER ON THE DUEL LINE TANK. IDLES OK THOUGH. ALSO IS THERE A WAY TO GET RID OF THE GLASS BOWL. THANKS
 
JB

JB

Honorary Moderator Emeritus
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Mar 25, 2001
Messages
45,907
Re: 56 FD-12 JOHNSON

FD-12 is a 1958, Dusty, but I think they started using fuel pumps around then. You may have an engine with merged parts. :) <br /><br />Please do not post in all caps. We view it as SHOUTING.<br /><br />Sounds like you may have a leak in either the pressure line or the fuel line, most likely at the connector. New O-rings are easy to install.<br /><br />Good luck, and welcome to iboats. :)
 
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itstippy

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Jul 17, 2003
Messages
548
Re: 56 FD-12 JOHNSON

You have two issues here:<br />1) The throttle should advance fully when the motor is in Forward. It should not advance fully in neutral. Yours is acting weird. Take the cover off, put the motor in neutral, and watch the armeture plate closely as you advance the throttle. The plug wires should stay out of the way, and the armeture should advance smoothly until a cam on it bumps up against the top end of the shift lock lever. Now shift the motor to Forward. The top of the shift lock lever should move outward, out of the way of the cam on the armeture plate, and the plate should now easily advance to full throtle. If that's not happening, please tell us what IS happening.<br />2) You are not getting enough fuel when you do get to WOT. When you say "pump the primer on the dual line tank" do you mean push the plunger on the gas tank up and down (pressure tank) or squeeze the rubber bulb on the fuel line (modern tank)? I think 1958 18HP's had pressure tanks.
 
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dusty221122

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Sep 27, 2005
Messages
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Re: 56 FD-12 JOHNSON

I made a new gasket for the pressurized gas can and replaced all hoses. Fixed most of my problems thank you to all that helped. I want to pick someones brain on actually how fast can I expect this motor to push a 14 foot tri hull fiberglass boat arcoss the water. I dont know if I still having a problem getting it up to wot. If not to much can someone help me on putting electric start this motor so my father can use it. He cant pull the cord hard enough to start thank you for your time
 
M

MCM

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dusty221122

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Sep 27, 2005
Messages
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Re: 56 FD-12 JOHNSON

ok i think i have a symptom to the motors inability to function correctly that you guys can help me with. the high speed adjustment has to be completely closed for the motor to run without sputtering the idle is fine now since i replaced all of the hoses. thanks mcm for the pics that should help out remarkably..
 
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dusty221122

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Sep 27, 2005
Messages
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Re: 56 FD-12 JOHNSON

ok im getting frustrated but i think you guys are leading me to the promise land on my fd-12. i hooked up the hose last night and adjusted the carb. spins up nicely but i put it in the lake and crap-ola it wont get to the same rpm can anyone tell me what this means.
 
Chinewalker

Chinewalker

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Aug 19, 2001
Messages
8,902
Re: 56 FD-12 JOHNSON

Hi Dusty,<br /> On a motor that otherwise "spins up nicely", and by that it would imply that the motor is drawing fuel, then your problem is probably that the motor is only running on one cylinder.<br /> Could be caused by one of three things. 1) Low compression in one hole. What are your compression numbers? 2) Blown head gasket. Any evidence of water on the spark plug? 3) No or low fire on one plug. Have you checked the ignition components. The original 1958 coils WILL be cracked. Replacement coils made within the last 30 years tend to be fairly robust. Points gapped at .020"? Condensers checked? Plug wires in good shape? Good clean set of Champion J4C or J6C plugs in there, gapped at .030"? With the motor running, under load, you might find that if you pull one of the plug wires off , no change is noted in the motor's sound. Or, you may find that it shuts off completely. Either way, you'll find the problematic cylinder...<br /><br />- Scott
 
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dusty221122

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Joined
Sep 27, 2005
Messages
10
Re: 56 FD-12 JOHNSON

Ive bought a carb rebuild kit and two new coils were going to get r done tonight and see what she will do this weekend if anyone has any info on the troubleshooting of my engines electrical system i would appreciated it very much. us green horns need all the help we can get......
 
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dusty221122

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Joined
Sep 27, 2005
Messages
10
Re: 56 FD-12 JOHNSON

well things have gotten interesting on the fd-12. rebuilt the carb this weekend and did some adjustments on the carb changed plugs to some j6c. took it out for a midnight run she planes good finally got it up out of the water. one thing the motor has to be choked for it to get to wot. i know that is not normal so if anyone can chime in and tell me what the deal is that would be very noble of you... oh yes she idles like a dream now. thanks
 
M

MCM

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Jun 1, 2005
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Re: 56 FD-12 JOHNSON

Hi Dusty,<br /><br />When you say it has to be choked to get to WOT, how much choke do you have to use?<br /><br />Mike :)
 
M

MCM

Lieutenant Junior Grade
Joined
Jun 1, 2005
Messages
1,201
Re: 56 FD-12 JOHNSON

I think you need to revisit the rebuild and make sure you haven't got some linkage hooked up backwards :rolleyes: , observe the choke valve to see if its performing as it should when you move the choke handle, double check the carb adjustments, somethings definately amiss.<br /><br />Mike :)
 
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