18 Horsepower Johnson Troubles

[Thompy_04]

Re: 18 Horsepower Johnson Troubles

Got the flywheel off, and replaced all the electrical componets (points, condensors, and coils) gets GREAT spark to both cylenders. Took the boat down to the marina today, and got it running to a certain extent. Tell me if this sounds like a carb prob. Hard to start, low pressure in the primer ball, and once started little or no idle. I could get it to run if I held the throttle open, and then shift, to get going. When I did get going I couldn't get on plane and only did about 5 had no top end at all. I figured the carb would need to be rebuild, so I went ahead and bought a carb kit. Need some info on fuel pumps for this 1960, if any info available give me a holler.

 

[Rick K]

Re: 18 Horsepower Johnson Troubles

Thompy,<br /><br />Read with interest this post. I have a '59 18hp that did the same thing as you described, only mine would whip right over and start. It would shake, shimmy, rattle, clammer, click, nock, shake again, swear at me, then die. <br /><br />I couldn't get it to even out. Although it had been sitting, and not serviced in a long, long time, I went thru and checked the points - looked ok. Coils looked ok. Since it started right up, I set aside any carb problems, temporarily. <br /><br />Then I checked the o rings in the fuel connector - they were shot. I changed 'em (a miserable job, you need some dental picks) and she fired right up. <br /><br />Of course, every engine is different. I think of them like any other engine - they get old, used, abused, and need service... Just have to keep up on it, that's all.<br /><br />Rick

 

[Thompy_04]

Re: 18 Horsepower Johnson Troubles

Well Rick, I think you hit the nail on the head bud. It does the SAME thing.... Shakes, rattles, then when I mess with the throttle it will roll, very slowly. Haha. I did think about the fuel connector, on the engine and on the fuel hose. Did you change the o rings on the engine hook up or on the fuel line? You can here some sort of leaking sound from the carb, and I'm getting very little pressure in the bulb so I'm leaning towards a bad float, or needle and seat. I believe I can buy a whole new fuel connector at my local marine store, and if I'm not mistaken even walmart so I'll look into that also. But thanks for the help!

 

[petrolhead]

Re: 18 Horsepower Johnson Troubles

Rebuild that carb for starters, then see what happens, maybe replace the connector or O-rings too, but don't do too much at once, one piece at a time and see if you can work out where the probem is by gradual elimination.<br />Good to hear everything now seems OK on the electrical side, for me that's the most baffling thing if it doesn't work, my grasp of electrics is tenuous to say the least!

 

[Rick K]

Re: 18 Horsepower Johnson Troubles

Thompy, all i did was replace the O Rings in my connector. The packings on the idle screws are kind of beat up, but I haven't changed them as of yet. <br /><br />By your post, I see you have a different type fuel system than mine. I have the dual-line system, with the pressure knob right on the tank. Same concept, I suppose. I'm sure that once you rebuild that carb like pertolhead said, your problems will go away.<br /><br />I found the motor pretty easy to work on, although I'm not to schooled on outboard engines. The Seloc Manual has pretty good drawings and procedures on the rebuild process.<br /><br />Would rather have a Chevy 350 to work on any day...<br /><br />Good luck!<br />Rick

 

[Thompy_04]

Re: 18 Horsepower Johnson Troubles

I know my post is a bit late, but I'm a night owl.... I rebuilt the carb today, and hopefully this will work out the probs. The carb looked clean inside and out, but still I rebuilt her. The packing nuts were absolutely screwed, stuck together and harder than sh*t to get out and clean off. Put two new ones in on each high and low needle holes. Float looked good and replaced needle and seat, and cleaned and blew out all passages. If this doesn't fix things, I believe I will move to the pump and lines. Because basicly THATS THE ONLY THING LEFT TO REPLACE!

 

[Thompy_04]

Re: 18 Horsepower Johnson Troubles

Well took the boat to the marina today, and found out that I still have the same problem.... But I took some advice that I found on this site and pumped the bulb to see if the fuel pump was bad... She purred like a kitten when the ball was pumped. Problem solved I believe.... Need some help finding a pump for this old girl, any ideas? I think this is a non serviceable pump so imma have to buy the whole thing. Still getting erratic spark, but one of the points was out of adjustment just need help on finding a pump... Thanks so much guys, helped me though a world of headaches.

 

[Thompy_04]

Re: 18 Horsepower Johnson Troubles

Another question, if I was to put a new impeller in, would I need some kind of seals, or gaskets to put on the leg when I break her down? She's shooting water out, I just don't think enough because the block is getting a little warm. Also could be a themostat and I'll end up changing that also. Just need to get this fuel problem fixed too. I can pump the primer ball and she'll run fine... and sometimes the primer ball will lose its firmness. Sound like a fuel pump to you guys? Any help would be great.... Thanks

 

[petrolhead]

Re: 18 Horsepower Johnson Troubles

You don't need any seals or gaskets to replace the impeller, you can use a smear of sealant under the impeller plate if you like, but I don't believe it's essential.<br />There isn't a gasket where the lower unit bolts to the leg, only where the gearcase bolts together and you won't be touching that to replace the impeller.<br />If the rubber grommet on top of the water pump housing, where the water tube fits, is in bad condition you'll need to replace that.

 

[Chinewalker]

Re: 18 Horsepower Johnson Troubles

Hi Thompy,<br /> It is possible to rebuild your fuel pump - might even just need a careful disassemblyand cleaning. A new fuel pump might run you around $50.00 and save you the frustration. Also, make sure the tank is properly vented. It has to have acccess to open air as fuel is drawn out or it creates a suction effect and will slow the fuel draw.<br /> When you do replace the impeller, make sure the o-ring at the top of the driveshaft is present and in good shape. And, put a good gob of waterproof grease in the splines at the top of the shaft.<br />- Scott

 

[Thompy_04]

Re: 18 Horsepower Johnson Troubles

In my manual it says you can't rebuild this type of fuel pump. The whole unit has to be changed. I haven't had time to look at the tank, and if I would where is the vent on the tank? I took the fuel pump apart and it looks good, but even a small crack in the diaphram would make it malfunction. Its has to be down to fuel line leak, tank leak, carb prob (but rebuilt it) or a fuel pump. The fuel lines on the motor look good, no cracks or rotting and line from the tank to the motor looks good also. I did replace the female connectors on the line to the motor on both sides. It just gets me that the bulb will get pressure before I start and then will die after about 30 seconds if not pumped. Any suggestions?

 

[Thompy_04]

Re: 18 Horsepower Johnson Troubles

Well I'm gonna reopen this post and see if I can get a response. I just got the thing running, sort of. It'll start right up first few pulls and idle REAL bad. Seems to run clean, then hit and miss, then clean itself out. Has no midrange and all, and when full thorttle is applied it seams to bog at first then almost hit another "gear" and kick in and stay open quite well. Will run at WOT pretty good w/o pumping ball. I will thorttle down and it will idle good, then go back to a bad idle again. I'm thinking about rebuilding the carb again? Changing the float and all. Or maybe the link and sync I did was way off. I've done this. Rebuilt carb, added new fuel lines and pump, new hose connectors, new points, condensors, and coils. Did a link and sync. Took head off and no scoring or pitting and pistons look good. Even 100 psi in both cylinders. Sometimes will run good other times, it will run like crap. I'm absolutely going nuts.

 

[Paul Moir]

Re: 18 Horsepower Johnson Troubles

Thompy - a couple questions:<br />Is the midrange always bad?<br />How about the spark plug wires? Any cracks, etc? <br />Is the carburetor leaking anymore? Primer bulb getting firm now and staying firm until you start the engine?<br />Pumping bulb have _any_ effect while running?<br />How do the spark plugs compare?

 

[Thompy_04]

Re: 18 Horsepower Johnson Troubles

1. Yes<br />2. Some, not down to the core though.<br />3. No, new float and now stays nice and firm.<br />4. Sometimes.<br />5. First check looked fine, tan brown on both. After I got home both were coal black.<br /><br />After taking the carb down again I noticed the high speed screw was WAY rich. Didn't get enough packing material in there and wouldn't tighten all the way. This obviously could have been the prob. Rebuilt carb again. Hopefully that will do it. Plugs looked fouled, but still getting hot blue/white spark from both. Will try new plugs in the AM and see if the rebuilt carb helped out. Anymore suggestions sure would be appriciated right now though.

 

[Thompy_04]

Re: 18 Horsepower Johnson Troubles

There you go hope you can work from that info and input I just put in, I appricate all help guys. Sorry to be such a burden.

 

[rrmcbride]

Re: 18 Horsepower Johnson Troubles

Try running the motor at home in a garbage can,,but have the fuel tank sitting higher than the motor..If it runs better like this you still have a fuel delivery problem..You did replace the "O" ring right???

 

[Thompy_04]

Re: 18 Horsepower Johnson Troubles

All new connectors.

 

[Thompy_04]

Re: 18 Horsepower Johnson Troubles

Wanna change the gear oil in this thing again on suspect of a leak but just want to run a check. Problem is my local marina sold me the last tube of OMC Premium Blend. They said they didn't have any more, and that no one around here buys it so they won't be getting more. Is there any other type of Lower Unit oil I can use, or am I doomed to drive or order of the internet? Also is there anyway I can get ahold of a pull starter spring? Mine broke, and have NO idea where to start.

 

[petrolhead]

Re: 18 Horsepower Johnson Troubles

According to my manual Premium Blend is fine in your engine, you can use Hi-Vis instead if you want, but being a manual shift either is OK.<br />Where has your starter spring broken, near the end I bet? If it's within a few inches of the end, take the little metal loop off the broken bit by drilling out the rivet, heat the remaining end to red/orange hot with a gas torch, allow to cool, centre punch it and drill a new hole, rivet the metal loop back on (you could use a small nut and bolt instead of a rivet, but make sure it can't come undone!)<br />I've done this with both my Johnson and the Evinrude, it works fine.

 

[Paul Moir]

Re: 18 Horsepower Johnson Troubles

I remember reading on this board a post by Joe Reeves where he says not to use OMC Premium Blend in manual shift lower units. OMC apparently withdrew the recomendation when manual shift lower units started failing in the feild. So feel free if not encouraged to use HiVis (equivalant to the 90W outboard gear oil they sell at walmart, etc) instead.<br />NAPA autoparts or Iboats 18-6501 is the replacement for your spring. Goes for less than $10. The dealer should have it as well. (Petrolhead - that's an America only place to buy. There are a couple NAPAs within walking distance of where I live but they don't carry marine parts. So I do the heat, bend, bolt trick to them them too. )<br /><br />I think you're on the right track with the carbs if the plugs were black. An air leak at the mixture control packing would really screw things up. Hopefully you've got it beat.<br />If you have doubts about the ignition wires, wrap em up with tape as a test. Or if you can find a sleeve that fits over the boot, that would work too (say a peice of bicycle inner tube). Spark is working hardest at mid-range throttle.<br />But it's probably the carb. Having the high end so far out would really screw up the medium speed mixture.