1958 5.5 hp Johnson Low Idle Problem

[pgdignan]

Gentleman,

I managed over the weekend to do to the following on my old outboard; replaced the recoil spring, rebuild the carb, replace the impeller, replace the prop pin and cotter pin, convert the two line fuel system over to a one line system using one of those pulse pressure vacuum pumps, and finally replaced the intake manifold gaskets on both sided of the manifold. I can get the engine started and it runs right nicely when throttled up, however I can't seem to get it to idle at slow speed. I have tried the initial adjustment setting of 1.5 turns of the needle from seated and it worked poorly. I brought it all the way in to 1/2 turn from closed and it idles a little better but it still doesn't want to run below the start point on the tiller handle. Any ideas?

 

[F_R]

Re: 1958 5.5 hp Johnson Low Idle Problem

Yeah, I have a question. How did you hook up the fuel pump pulse line?

 

[samo_ott]

Re: 1958 5.5 hp Johnson Low Idle Problem

Ared the coils good? If you're sure everything else is good then the carb is still the prob and dirty. Did you clean below the dime sized disc on the top? Replace the float?

 

[pgdignan]

Re: 1958 5.5 hp Johnson Low Idle Problem

FR: I hooked up the pulse line to the intake nipple thing after plugging up one of the two ports used originally for the pressure system. Honestly followed the instructions I found on a different site http://www.outboard-boat-motor-repair.com he had the whole procedure with photos for a 5.5. It seems to work fairly well. Don't have the manual handy so I can't tell you exactly which opening (it's on the bottom part of the intake when you remove it, two circular ports with a rubber piece that fits over them with a spring like device to keep them shut when the engines not running.)

Samo: Don't know about the coils, could you recommend a specific check or should I just examine them for signs of damage/cracking. I didn't replace the float, it seemed to float just fine when I checked it (dropped it in some gasoline). As for the dime sized disc, I haven't touched it. I bought the rebuild kit and followed the instructions in the Seloc manual but it didn't mention the disc. Is that something I should be digging into?

 

[F_R]

Re: 1958 5.5 hp Johnson Low Idle Problem

OK, I was wondering if you plugged the unused port. If you had not, the air gets transferred back and forth and will kill any chance of a good idle.

Tell ya what, if it had been me the coils would have been the first thing I would have looked at. Unless they have already been replaced, they are ALWAYS bad on a 1958 OMC. Always!

 

[samo_ott]

Re: 1958 5.5 hp Johnson Low Idle Problem

Yep, it will probably need coils. But the carb is probably still the issue. If you did not remove the plug and clean below it you will need to do so. It is the low speed ports in there and they gunk up. A new plug is in every carb kit I have ever seen... The same website that tells you how to add the fuel pump I believe tells you how to rebuild the carb also.

 

[pgdignan]

Re: 1958 5.5 hp Johnson Low Idle Problem

You guys are the best, thanks. I'll yank the plug out tonight and go to town with some carb cleaner. How will I know if the coils are bad. In my prior life I can remember checking automotive coils using an ohmeter or voltmeter etc. Are there any specific checks for the coils (and if I do need new ones where can/should I buy them.) Thanks

 

[lexkyboater]

Re: 1958 5.5 hp Johnson Low Idle Problem

Assuming points and condensors are good, or replaced, you can check spark with a spark tester. See http://forums.iboats.com/showthread.php?t=213548&highlight=spark+tester. You can check coil primary and secondary resistance with an ohm meter. Primary resistance between green and black should be about 1.0 ohms, while secondary resistance between green and plug wire connection should be around 90,000 ohms. I had some older coils off a 71 9.5 HP which may have been okay in trying to trouble shoot a performance issue and they were 77,000 and 80,000 ohms. The new OMC coils I got were 92,800 and 93,800 ohms. This should probably be the same for a 1958 model.

 

[pgdignan]

Re: 1958 5.5 hp Johnson Low Idle Problem

I checked the coils and got the following results: between the black and green wires 100,000, the secondary resistance between green and plug wire was about 50,000 on both. I don't know if that means that they are good, bad, indifferent or just prone to being cranky. I replaced the coils and the condensers et. al. with new coils and a tune up kit but haven't gotten the chance to try and fire the thing up yet since it got dark before I could finish. If you have any parting words of wisdom before I finish reassembling and start cranking tomorrow please feel free to pass them on. Thanks again.

 

[F_R]

Re: 1958 5.5 hp Johnson Low Idle Problem

Somebody around here is reading their ohmmeter wrong. Primary resistance should be about an ohm. Secondary resistance should be somewhere around 7 k-ohms.

 

[pgdignan]

Re: 1958 5.5 hp Johnson Low Idle Problem

FR - you would be correct sir, I have just rechecked the primary resistance and it is precisely nil, nada, zero. Just to be sure I have this correctly, I put one lead from the ohmeter on the green and one on the black wire (same coil) with the coils removed from the motor. I take it from reading this string that the coils, between the black and green wire, should display some type of resistance. If that's the case then these were faulty, however they did enable the motor to run at mid range and higher. I don't confess to knowing much about the voodoo of coils, magnetos and ignitions in general, but would a coil without any primary resistance still generate spark sufficient to fire the plug or am I pipe dreaming?

 

[lexkyboater]

Re: 1958 5.5 hp Johnson Low Idle Problem

As F_R said, the old coils don't hold up well and I've read other guys here saying they worked on the design and improved as time went on. I would think if coils didn't have a primary resistance they wouldn't fire at all? Maybe the resistance is just really low? Were the coils oozing any black gunk, which would indicate they're toast? I had an early 90's yz 125 dirt bike that had a bad stator and it wouldn't start with the kick start, had to be roll started before the stator would fire. I wonder if bad coils don't fire at low rpms, which would lead me to the question how you got it started? You can't roll start an outboard!

Also, after you replaced coils and condensors, I assume that included points? After you replace all that, you still need to perform the spark test, just to make sure it's firing right. You might consider replacing plug wires too if they're old at all. One of mine on a 71 Johnson 9.5 was bad and spark jump on my tester was only 1/4 inch and a dull yellow spark. After new coils and plug wires, spark jumped 5/16 inch and was nice and blue! You want to confirm each component is working before proceeding to the next to prevent trouble for yourself.

That said, I'm with samo - seems like a carb problem. Sounds like you've already set idle speed mixture, but another guy that posted a problem with a carb found that it idled rough and stuttered till it got up to higher speed. Ended up being plugged ports behind the larger core plug, the one with the three tiny ports in the carb throat, and in fact all were plugged solid he said. See pic of a 71 Johnson 9.5 HP carb where mine was partially plugged, before and after pics using a flashlight. On my 71 Johnson 9.5 HP not revving out thread, I had to remove my carb a second time after a rebuild to replace the core plugs and soak it in carb cleaner to properly rebuild it after I didn't do it right the first time. I was rewarded for my effort and got it revving and running nice after some effort!

 

[pgdignan]

Re: 1958 5.5 hp Johnson Low Idle Problem

Lexky, thanks for sticking with me on this abhorrent situation but I think I finally have the problem licked. I was checking on some other posts and realized that I had made a couple of critical mistakes in the final set up. First after I put the coils, condensors and points back on the motor and got everything lined up so it looked pretty good. Then I yanked the carb one more time and took the low speed jet out and got a strand of copper wire and ran that through the three little holes on the jet, it turns out they were plugged and my earlier cleaning hadn't cleared them (I had previously yanked out the little metal plug on the top of the carb and cleaned it thoroughly). I put the carb back on and gave it a shot. It ran but once again didn't want to idle down properly. Frustrated I did some searching on the forum and realized I hadn't done the "Link & Sync" thing with the cam follower and the other stuff whose name I don't remember. Long story short once the carb timing got straightened out it idled like a champ!! Gotta love a 50 year old motor that still has parts available off the shelf and that can be disassembled and reassembled with little more than a screwdriver and pair of pliers. For everyone that spared me the time, THANKS AGAIN! Couldn't have gotten it done without you.

Pat

P.S. My four little nephews thought the old motor was the coolest thing ever.

 

[lexkyboater]

Re: 1958 5.5 hp Johnson Low Idle Problem

Ah, the old link and sync bites again! Super you got it running. Gotta love it when the young uns take an interest in the outboards! --Steve

 

[pgdignan]

Re: 1958 5.5 hp Johnson Low Idle Problem

Gentlemen,

I took the old Johnson out for a run over the Labor Day weekend. It ran pretty flawlessly for 8 straight hours on Saturday and a couple of additional hours on Sunday. As soon as I get some pictures downloaded I'll put 'em on the sight. Thanks again, the motor starts on first or second pull every time now.

P.S. I think I got alot of comments on my "classic" motor