'59 Johnson troubles

[rpg]

I've just gone through my '59 5 1/2 after sitting for about 14 years.<br /><br />New impeller, powerhead gasket, head gasket, thermostat, points, condenser, plugs (gap set to .020"), plug wires, carb rebuild, and complete fuel tank overhaul.<br /><br />I got it startedand it revved great but it will eventually lower it's rpm and not idle unless both high speed and low speed needles are fully seated (turned in all the way). And in that case, the throttle needs to be wide open for the engine to run at about 1,000 rpm. <br /><br />Float level was checked and set and overall the carb looks in perfect shape. And engine is developing pressure to keep the original tank pressurized.<br /><br />Any help would be greatly appreciated. Have sentimental value attached to this old girl. <br /><br />thank, <br /><br />RPG

 

[rwise]

Re: '59 Johnson troubles

Originally posted by rpg:<br /> plugs (gap set to .020"), <br />

pointS to .020 plugs to .030<br /><br />sound like the carb has a problem though.

 

[Paul Moir]

Re: '59 Johnson troubles

A agree - sounds like your running real rich. When you rebuilt the carb, did you get a new gasket on the main jet (brass tube that goes from the bowl up to the throat)? The gasket goes over the jet and seals it against the bowl.<br />Pumping the primer bulb make any difference?

 

[rpg]

Re: '59 Johnson troubles

thanks for the replies fellas. When I first fired it up, the carb was flooding. (I last played with the carb 14 years ago so thought everything was cool). When I took it apart and cleaned everything, the float needle was stuck, which explains why fuel was pouring out the carb on startup, but all the other jets, etc. looked very clean. Re-assembled and the carb wasn't flooding any longer but the other problem started. (Not running unless both needles were fully seated)Think I'm going to buy another rebuild kit and go with that. <br /><br />btw, there isn't a primer bulb on the tank as this is the older system which uses a button (on the tank) to prime the carb. Once the engine starts, positive crankcase pressure from the engine "pressurizes" the fuel tank to keep the engine running. I think 1959 was the last year Johnson did this. Then they went to the bulb system. <br /><br />thanks again for your help. My grandfather bought this little engine new and I would like to use it for trolling/fishing if possible.

 

[CATransplant]

Re: '59 Johnson troubles

I'll bet that needle still isn't seating properly there. It's not leaking enough to actually flood the engine, but enough that you can't use the actual orifices to supply fuel. It's running, but not correctly.<br /><br />The answer...rebuild the carb and install a new needle and seat.

 

[Paul Moir]

Re: '59 Johnson troubles

RPG, I almost forgot this site:<br /> Tom Travis' 5.5hp website.<br /> <br />CATransplant, the gasket I'm refering to is the large one you can see on the main jet here:<br /><br />

<br /><br />Those things crush quite a bit when you first fit the bowl, and they tend to leak (perfusely) if disturbed causing the engine to run rich. Pretty well only that and a needle/seat leak will cause the carb to run that rich. They're not present on all carbs though.

 

[rpg]

Re: '59 Johnson troubles

Paul, thank you very, very much for the excellent link. Think I'm looking at the carburetor for most of my problems now.<br /><br />Rick