18 Horsepower Johnson Troubles

[Thompy_04]

Re: 18 Horsepower Johnson Troubles

Yea, today I went through the carbs at least 4 times all together. Me needle kept sticking and wouldn't allow fuel into the bowl. I finally went back to the old needle that looked new anyway and it works just fine. I replaced all the packing nuts, and reset both jets. Its running funny also because I just came to find out that the choke will work itself half closed. Is there anyway I can take this electric choke off, and just use the pull choke? Ran great when I held the choke down, but then ran into a fuel line prob. Got new lines and will replace in the morning. Hopefully THIS WILL WORK.

 

[Paul Moir]

Re: 18 Horsepower Johnson Troubles

Sounds exasperating!<br />New fuel lines on an old motor are a must. Do yourself a big favour and get some worm type (aka normal) stainless clamps to go with it - no more fussing with those wire ones. <br />Perhaps the new needle was getting crudded up by bits of old fuel line? Did you happen to pull the seat to see if there was some bits up above there?<br /><br />I believe you should be able to simply remove the electric choke's linkage and it'll work manually like it's supposed to. There should be a spring that holds the choke open. Is yours missing?

 

[Thompy_04]

Re: 18 Horsepower Johnson Troubles

No the spring isn't missing, but the electric choke is actually what gives it spring to go into the down position. When you pull the choke lever with the electric choke off it works just fine, but when you push it to turn it off it simply just stays in the open position. And no my electric choke isn't missing, its just holding the choke half on. I actually did find some fuel line in the seat, wasn't much but the needle had a rubber tip for good seating I suppose and it was getting stuck.

 

[Thompy_04]

Re: 18 Horsepower Johnson Troubles

Got the motor running real well today, except for just a couple of things. Starts right up and idles good, midrange still a little funny. At WOT runs like a champ and will idle down to midrange and sputter then idle well. The midrange is still funny, so what are some things that could give midrange trouble? Also if it idles longer than 5 mins the carb bowl runs dry and will kill the motor. A fuel bulb pump or two and she runs perfect. Any suggestions?

 

[55Crestliner]

Re: 18 Horsepower Johnson Troubles

I'm having very similar problems with a 55 10 horse. I've done ALL the electrical stuff, (wires also), and the carb rebuild, had it appart twice. The Pressure tank holds pressure, but the engine coughs and dies very quickly after startup. For a while the sediment bowl was going down in level, and priming the button on the tank would bring it back up. Sorry for jumping on your post, but just wanted to let you know you're not alone here!<br /><br />I'm wondering about the float, perhaps it's sticking? Or the needle valve is not dropping? You mentioned yours is sticking?

 

[Paul Moir]

Re: 18 Horsepower Johnson Troubles

Thompy - <br />About the electric choke - is it the boot around the solenoid that is causing the trouble, or the spring behind it? Just peel back the boot to find the spring. Actually, the entire end of the solenoid is held in by that boot. I forgot that the electric chokes rely on the solenoid to return, and only the manual ones have a return spring.<br />About the needle sticking - I was under the impression it was sticking the other way on you - open, not closed. Often that sort of condition is caused by a bit of crud keeping the needle from fully seating. Anyway, sticking closed may be caused by your weak fuel delivery. It's not developing enough pressure to push the needle down.<br />About needing to pump the primer bulb - either the fuel pump is weak, the primary compression on the crankcase half that drives the fuel pump is weak, or there's some constriction in your fuel supply. You can eliminate supply problems by trying another tank and line if one's available. The most common constrictions are from the fuel pickup screen inside the tank, or from a faulty primer bulb. But I doubt this is your problem since it ought to cause more problems at WOT than at idle.<br />I would at least disassemble and clean the fuel pump, as tedious and delicate an operation as that is. If there are any pinholes in the diaphram it'll need to be tossed. Despite what Seloc says, I would check with the dealer for a repair kit before getting a whole pump. I know for a fact that they do have them for the smaller fuel pump as well as the one with the glass bowl.<br />For the midrange problem - that's a tough one. Midrange problems suggest to me bad timing or conceivably a primary compression problem. Or even a holed fuel pump diaphram problem. If it's a primary compression/fuel pump problem, then you should see a difference in your spark plugs after running a bit. As for timing - are you sure you have your link&sync set correctly? You monitored the butterfly opening, not the pickup moving right? If so, it could conceivably be that the points are set a little wrong. I know a way to verify your points setting, but it requires an automotive timing light. Do you have on or have access to one?

 

[Paul Moir]

Re: 18 Horsepower Johnson Troubles

55Crestliner - Sounds like you're sucking air at some point. Often this is caused by worn out o-rings in the fuel tank connector. Have a look at this post to see how to fix them:<br /> Discussion, click here.<br /><br />Try posting your own thread with a title like '55 10hp fuel supply problem' or something and you'll get lots of good help.

 

[55Crestliner]

Re: 18 Horsepower Johnson Troubles

OK, I'll try a new post.<br />(I did do the O-rings in the fuel tank hose, just last night I hooked the hoses directly to the carb and air outlet, bypassing the connector completely. No diff.)

 

[55Crestliner]

Re: 18 Horsepower Johnson Troubles

My motor is fixed!<br />I didn't have the fast and slow needles out far enough. I had them adjusted at 3/4 out for the top, and 1 1/2 for the bottom. They needed 1 more full turn out.<br /><br />I found this because I just rebuilt the 18's carb, and I didn't have the face plate on. I was adjusting the needles, and it did the exact same thing the 10 did, run, then cough, then run...<br /><br />Again, sorry for jumping on your post, but I'm so exited that it's fixed, I can't help but wonder if this is your problem too - it' sure sounds like it. I went with 3/4 and 1 1/2 because of recomendations by another repair site. Then when I got the carb kit for my 18, it had directions <br />It said to start with 1 turn out for the top, and 2 for the bottom. If I turn the screws in a half turn, it does the same exact symptoms on BOTH motors.<br /><br />Hope this helps

 

[Thompy_04]

Re: 18 Horsepower Johnson Troubles

The boot looks like it is in the way because a piece hits it, but it looks like the spring isn't coming out far enough to totally let the choke in. No I don't have a timing light in handy Paul, but I have changed out the old pump and put a new 2" inch square type pump. The motor didn't do this till recently. Acutally now that I think about it the midrange didn't do this till I had a little prob. My plate that hooked the twist grip throttle to the armature plate came off, thus making me take off the armature plate. I think that one of the plug wires might have come lose from a coil. I have had this prob in my little adventure to get this thing running, and its showing the same symptoms. As for dying at idle I've been through the carbs 5 times, new fuel pump. BUT, I changed the fuel lines and they didn't have the right size so I went to a size SMALLER. Yes smaller, I figured I could get a little better seat on the nozzle from the pump seeing is how the other lines were leaking because of the size. By the way, I would like to know the fuel line diameters so I might be able to hook up the correct sizes. This could cause the idle prob because it didn't start till I changed out the lines. Maybe the fuel restriction is there. I will get to this as soon as possible, but time wise I'm a little pressed this weekend. But a response could help me out if possible. Sorry for the long post just trying to get everything out. Thanks alot guys.

 

[Paul Moir]

Re: 18 Horsepower Johnson Troubles

A poor spark plug wire connection would certainly explain the midrange problem. If you've got the German made coils (the Sierra grayish green ones), the metal stake in where the spark plug wire connects to them is threaded. If you turn the spark plug wire while installing it (ie, screw it in), it'll grip the wire really well. Put some grease on the wire to make it slide in easily. Also, make sure the boots are not about to fall off the wire - the connection there can be flaky too. If you have a multimeter handy, you should measure about 5k Ohms between the spark plug terminal in the boot and the engine block if the connection is good.<br />The lines ought to be 1/4". At idle since there's such a low flow rate, if they were too small that should not affect pressure. In fact, when you do hear on this board about undersized fuel lines causing problems, it's always at or near WOT.<br />Did you change the hose clamps out from those horrible wire ones?

 

[Thompy_04]

Re: 18 Horsepower Johnson Troubles

Oh yes, I changed those awful things out. Absolutely a HORRIBLE job trying to get them back on and once on they really don't grip much. Like I said I can reply to the message but I really can't get my hands dirty. I'm going to go through the plug wires because I'm almost sure that the prob. The plug wires are the same from '60 but they aren't cut down to the wire and see no reason in changing them. The coils do though have a studded post to connect the wires too, so I might try to rig something up to hold them on the coil itself better. Its coming along and I have been very surprised with this motor. Didn't even expect to get this far, and it pushes my '60 Monark V-Bottom quite well. Thanks for all the help once again!

 

[Thompy_04]

Re: 18 Horsepower Johnson Troubles

Well I would call this a success. Today I took the amature plate off and found that yes, my plug wire did come loose from the coil. Reactached it, patched it up with some electrical tape, and then checked the point set. Took it down to the marina and it ran like a champ! Idled down real low and had good WOT, not to mention better midrange. I did some tinkering with the carb jets and improved it even more. Dies a little at idle sometimes but think its in the tank or something, not a big deal. Still am very happy. Thanks for all the help and advice getting this oldie but goodie goin'!

 

[Solittle]

Re: 18 Horsepower Johnson Troubles

Great thread & one we can learn from.<br /><br />Thanks guys