1966 johnson 40hp wont run

ifishy

Cadet
Joined
Dec 11, 2011
Messages
9
okay so I have a 66 40hp and most of the year it ran well I had some stalling in the fall and someone told me to get some ethanol treatment for the gas. I did that and the next time out it stuttered a few times early than ran well the rest of the day. At this point I got a little money for my b-day and invested in a new starter as I had been pull starting for 5 years. i put in the new starter and the next time out I had trouble getting it to run it would turn over rev way up than die when I finally got it to go for a second and tried to throttle down it would stall out. now it has always had trouble with the throttle all the way down but would still idle at a couple clicks above lowest throttle that would turn into a good trolling speed 2.5 mph or so. this last time I couldnt get anywhare near that rpm set without stalling. the slowest I could go was about 5mph. after some reasearch I decided to rebuild the carb and got some help from here and finished that. its doing the same thing where it will start rev up than stall. I noticed that when I primed it fuel squireted out of the fuel pump. I tightened the screw in the center and let it sit and soak for a minuet and that problem went away but the engine still will not stay running. I gave up and winterized it as this week would have been my last chance till spring. I'm not ready to give up on the motor all togather as it has been good to me for the last 5 years and I dont have the money to replace it. is there anything I could have done when I replaced the starter that would cause this? or could it be the fuel pump and the timing is coincidence. the starter is assmbly included a bracket and a plastic lever like piece attached to it. I got the starter from a starter specialty place and they attached it to the bracket for me the plastic piece is still there and in the same position it was before I toot it off. i'll take any advice I can get I have all winter to work on it but wont be able to try starting it again till spring when I do new plugs and oil. also when I rebuilt the carb I pulled and checked the plugs they were very clean in fact cleaner than normal for this time of year but the back end where the wire plugs in was loose (partially unscrewed). I didnt even know they came apart like that. I have always used champion j6c plugs but this year my normal store didnt have them so the gave me a different brand that they said was the same thing just a higher grade (they cost about a buck more each). again i didnt have any problems untill this fall and the biggest problems happened when I got the starter.
 

HighTrim

Supreme Mariner
Joined
Jun 21, 2007
Messages
10,486
Re: 1966 johnson 40hp wont run

Im assuming you bought NGKs? Throw them in the trash, they are not higher end at all, put the Champs back in.

Have you started with the basics? Checked spark and compression?

Any chance their is water in the tank? Was there water on the plugs when you pulled them>?

Air leak in the fuel line? Did you replace all the original lines? Try a different tank/lines/bulb?
 

scanman

Petty Officer 1st Class
Joined
Jul 29, 2010
Messages
370
Re: 1966 johnson 40hp wont run

Sounds like water in the fuel to me too. Other than that an air leak. Do you have a fuel filter in-line? That's cheap to try & can cause the same problems. I also agree, THROW OUT THE NGKs, if that's what ya bought!
 

ifishy

Cadet
Joined
Dec 11, 2011
Messages
9
Re: 1966 johnson 40hp wont run

the bottom plug had water on it when i pulled it the top one was dry I bought an inline filter but didnt put it in yet as I wanted to make sure it was running right first. the boat stores in the garage with a sealed tank but i suppose some condensation could have gotten in there. the original lines got replaced 5 years ago and the line from the tank with the bulb was new 2 seasons ago. it is a portable tank as its only a 14ft boat. I would be nice if it were just that simple as an air leak or water in the fuel. once primed the bulb stays firm for at least 20 mins after that I stoped checking. as far as the brand I want to say they are bosch but i'm not positive that parts store has been really good to me for auto parts for the last few years and is the only place I could get the champs for the past 3 this year they didnt have them I will try for them again in the spring though. Like I said they worked fine most of the year its only recent that I have had the problems. I will get some new lines for the spring along with a new main line and try putting in the inline fuel filter as i already have it. should I worry about the leak in the fuel pump or do the screws sometimes loosen up a little like that? i have had some vibration loosening with the screws on the recoil in the past.
 

1946Zephyr

Vice Admiral
Joined
Oct 21, 2008
Messages
5,556
Re: 1966 johnson 40hp wont run

Check the compression on that motor. If the bottom readings come out low, then it's a safe bet that you have a bad head gasket. If there was water in the fuel, then you would most likely find water on both plugs. That motor would be good to have at least 100 psi per hole.
 

kfa4303

Banned
Joined
Sep 17, 2010
Messages
6,094
Re: 1966 johnson 40hp wont run

Hi ifishy. Here are some handy links to help you get and keep that old gem running. You should be able to get most routine parts you need right here at iboats. As per the previous posts, check the compression, spark and fuel and report back. Holler if you get stuck.

http://forums.iboats.com/showthread.php?t=158086

http://www.duckworksmagazine.com/04/s/columns/max/24/index.cfm

http://forums.iboats.com/showthread.php?t=167352

http://www.iboats.com/Johnson-Outbo...0715452--**********.556348767--view_id.271265
 
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