Help FD 10 1956 15 hp Johnson

abibergall · Jul 22, 2010

Please help I am a novice I have a Johnson model FD 10. I bought this motor with pressure tank for $75. I rebuilt the carb with a carb kit I bought. I replaced the main gasket, the float the float pin and cleaned the carb parts real good. I put it back together and I simply cant get it to run more than about 30 seconds. I set the low speed setting to 2.5 turns out and the high speed to .75 turns.

I am looking for any advice on best practice for starting the motor and to make sure there is nothing basic that I did wrong when I rebuilt the carb. Is there a way to set the float or the float pin that goes in under the float?

Sorry if these are dumb questions I really want to get this thing running.

Daviet · Jul 22, 2010

Re: Help FD 10 1956 15 hp Johnson

Will it keep running if you keep pushing the primer on the tank while it is running?

abibergall · Jul 22, 2010

Re: Help FD 10 1956 15 hp Johnson

Tried that does not seem to help. I checked the tank and it seems to hold good pressure. I think this is the case because when I loosen the cap it makes a pssst like sound etc. I also replaced the gas lines with new today. I got it to run for about a min. but it always dies. I actually have open blisters from pull starting this thing about 1000 times. i will not give up just give me advice and thanks to all that help.

lindy46 · Jul 23, 2010

Re: Help FD 10 1956 15 hp Johnson

If you have good compression and spark, then there is some crud still in the carb. Did you remove the welch plug from the top of the carb and clean the openings under there? Replaced gas lines on both motor and tank? I just went through the same situation on the same motor I tuned up for a friend. It ran great for me when on my tank. My friend took the motor home, hooked it up to his tank and started having similar problems. It would run for a few minutes and then quit. I took the carb apart again and it was full of crud - crud coming from his tank! Cleaned out his tank and replaced the gas lines, and no more problems.

1946Zephyr · Jul 23, 2010

Re: Help FD 10 1956 15 hp Johnson

The low speed needle should only be 1 1/2 turns out, not 2 1/2. You could possibly be running it too rich.

Have you checked the condition of your ignition system? You could possibly be running on one cylinder, due to a bad coil. These motors actually run pretty decent on one cylinder.

abibergall · Jul 23, 2010

Re: Help FD 10 1956 15 hp Johnson

Can you describe the Welch plug not sure what that is.

abibergall · Jul 23, 2010

Re: Help FD 10 1956 15 hp Johnson

is there a good process to follow to clean out an old pressure tank. I have heard about rolling around bb's etc to loosen any rust etc. Otherwise I would plan on just draining the gas and flushing out with water and then drying it real good with air etc.

abibergall · Jul 23, 2010

Re: Help FD 10 1956 15 hp Johnson

Thanks I will start over again at 1.5 turns out. sorry for another dumb question but I am running a 50:1 mix ratio. I did this because the guy at my repair shop told me I did not have to use 24:1 as long as I used a quality oil. Is this accurate or could this be adding to my problem.

1946Zephyr · Jul 23, 2010

Re: Help FD 10 1956 15 hp Johnson

Well, manufacturers specs say to use 24:1 on that motor, but that motor does have a needle bearing set up on the crank and rods, so you can get away with 50:1. However, the alloy in the pistons in those older motors is a bit softer and sopposedly scores more easily than the newer motors, so be careful and make sure it runs cool at all times. The later motors that were built with thermostats, run warmer, therefore making the metal parts expand, which will make moving parts "closer together" Your old motor has no thermostat and runs cool all the time (providing your impeller is up to parr) so less worry about running hot. Thermostats were put into motors in '59. Just my two cents on oil mixes.

Bottom line is: Stick with the maufacturer's specs and you'll have less worry.

turtles11756 · Jul 23, 2010

Re: Help FD 10 1956 15 hp Johnson

did you check ignition coils, points, condensers, wires ? the spark needs to jump a quarter inch gap or better

1946Zephyr · Jul 24, 2010

Re: Help FD 10 1956 15 hp Johnson

turtles.....you didn't read my earlier post.

abibergall · Jul 24, 2010

Re: Help FD 10 1956 15 hp Johnson

Hello yes I did read your post sorry thought I responded I am new to this.

abibergall · Jul 24, 2010

Re: Help FD 10 1956 15 hp Johnson

Have not checked into the electrical stuff yet I was hoping to avoid it as I have never worked on this stuff yet. Does anybody have a good blow by blow on how to go through the process.

rjezuit · Jul 24, 2010

Re: Help FD 10 1956 15 hp Johnson

Beg to differ, but 24:1 it is. There are no roller bearings on the pin end of the connecting rod. Rick

Help FD 10 1956 15 hp Johnson

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