Performance of 1967 5hp johnson question.

[cjist1]

I took my motor out today for the first time. I recently rebuilt the carb and installed a new fuel pump. The motor starts great and runs smooth. I managed 5 - 5.5 mph in a 12' Al sears boat with 2 adults (400 lbs total). This speed was taken from a handheld GPS. Does this seem about right? It seemed a little slower than what I expected. Seemed like the motor was not revving to its potential. Also, the motor idled best with the mixture knob turned out about 1 turn or so. Full throttle was best with the knob turned all the way in. Does all of this seem normal? Just wanted to see what everyone thought. Thanks in advance.

 

[Paul Moir]

Re: Performance of 1967 5hp johnson question.

12' Al boats can be real trouble to plane sometimes, so yes it may be normal. My 4hp on a 12' hull with just me in it, trimmed and weight distributed perfectly only achieves 5.5 knots. Compared to the 6hp on a 16' Al hull which runs around with two adults at 14 knots or so.<br />But your needing to adjust the carburetor makes me suspicious. Next time you're out, try disconnecting each spark plug wire using insulated pliers so you're only running on one cylinder. Note if the full throttle power drop is different for one or the other cylinder. <br />It's possible the engine is running excessively rich too. That's easy enough to check. Directly after a full throttle run, shut the engine down. Then remove the plugs and examine their firing ends. They should be tan to chocolate brown in colour with little or no deposites, and they should look pretty well identical.<br /><br />It's probably nothing so do those tests at your leisure.

 

[Chinewalker]

Re: Performance of 1967 5hp johnson question.

That 5 on a modest 12-footer ought to plane off. It's based on the 6hp powerhead and has a fair bit of kick to it. <br /><br />I agree with Paul - something is not quite right yet with the motor...<br /><br />- Scott

 

[cjist1]

Re: Performance of 1967 5hp johnson question.

What would cause a rich condition? There is no other adjustment on the carb other than the mixture knob....right?

 

[Paul Moir]

Re: Performance of 1967 5hp johnson question.

There's only a few possibilities:<br />Leaking fuel pump diaphram - that only affects one cylinder so the spark plugs will show it.<br />Leaking grommet around the main jet in the carb. Since you have a fresh one there we should be able to assume it's OK.<br />Leaking needle and seat - that's relatively easy to diagnose, pump the primer bulb and observe if fuel comes out of the carburetor's throat.<br />Incorrectly set float - It would need to be far out to have a dramatic effect. And it should be freshly set.<br />Sunk/sinking float - Fresh one there so that should be good.<br />Incorrect or missing high speed oriface - very unlikely.<br /><br />Either way, to diagnose a rich condition pull the plugs and look for carbon deposits or black insulators. The engine will be extra smokey too. The mixture knob is only supposed to affect the idle mixture. Now it does change the full throttle mix slightly but it shouldn't be significant. The fact that cutting off the extra fuel from the idle circuit makes the engine run better suggests to me either it's receiving too much fuel, or that's compensating for the incorrect throttle butterfly angle for the engine RPMs in the case of a missing cylinder. But in that latter case I think the adjustment would be the other way.

 

[cjist1]

Re: Performance of 1967 5hp johnson question.

Well I pulled the plugs, it seems that its dropping the bottom cylinder. I have new points and condensors and they are adjusted properly to .020". Could it be one of the coils? Can the coils be checked?

 

[tashasdaddy]

Re: Performance of 1967 5hp johnson question.

you can swap the coils position and see if the problem follows the coils. tha will tell you wich soil is bad.

 

[Paul Moir]

Re: Performance of 1967 5hp johnson question.

The coils are very easy to check, just closely examine them for cracks in their insulation. That is the only way they ever fail. Another thing that's worth checking is the spark plug wires themselves. Again look for cracks.<br /><br />A completely healty ignition system on that outboard will be capable of producing sparks 3/8" long, perhaps a bit longer. If you can do that, everything is good and the points & coils are adjusted properly (or close enough).

 

[cjist1]

Re: Performance of 1967 5hp johnson question.

Ok, I checked the ignition. Both cylinders are getting very good spark. I used a tester and they are at least 3/8" long. I think I found my problem though. The little o-ring gasket that goes into the carb around the mixture screw...it was all falling apart. Can I use a rubber o-ring in replace of that? Cause I dont know where I would get on of those cork type ones.

 

[Paul Moir]

Re: Performance of 1967 5hp johnson question.

Those are just packing, they're normally very crumbly. O-rings don't work very well as replacements because the "friction" never gets right. A working alternative is to use teflon packing from the plumbing department. Naturally the proper packing from the dealer is best, and very cheap.<br /><br />While you're looking at the carb, how's that gasket on the main jet looking? With the carb upside-down, is the float nice and level with the casting's rim?<br /><br />What evidence do you have that it's dropping the bottom cylinder? I mean, what does the spark plug look like? Is bottom compression healthy? I believe on your engine the fuel pump is connected to the top cylinder so that shouldn't be an issue.

 

[cjist1]

Re: Performance of 1967 5hp johnson question.

Well, at first I thought that the bottom cylinder may have been cutting out just because the plug looked like it was running way richer than the top one. I did adjust the float just now...thanks. That may have been an issue. I will need to order some packing washers online. I did find an o-ring that seems to fit really snug, so im gonna go try that. Thanks for all the help.

 

[cjist1]

Re: Performance of 1967 5hp johnson question.

I cant figure this thing out. Its running way rich. Is it possible to have the wrong size jet in it? Are they marked with a number? I cant think of any other possiblilties.

 

[Paul Moir]

Re: Performance of 1967 5hp johnson question.

I don't think so. Perhaps someone tried drilling it out to improve performance, but I really doubt that.<br /><br />Go through my list again. There are not many ways to get extra fuel in the engine. <br />The fuel pump diaphram may be checked by unscrewing it from the engine and pumping the primer bulb. If you see fuel come out the back, it's ruptured.<br />The needle/seat could be leaking. Pump the primer bulb while it's running. If it runs worse, they're not doing their job.<br />The fat main jet gasket is a frequent culprit unless it's fresh. That's part 39 here:<br /> http://epc.brp.com/Scripts/ImgServ....04\04.TIF&ilSC=40&ilIV=0&ilBR=0&ilIF=G&ilRE=8 <br />Leaking packing normally makes the engine run lean, so I don't think that is likely the problem.

 

[cjist1]

Re: Performance of 1967 5hp johnson question.

I bet its the main jet gasket. Does that part come in a carb rebuild kit? I dont remember replacing it when I rebuilt the carb. The fuel pump is band new..so i doubt its that. Where can I get that gasket from? Thanks. Im gonna take the carb apart tomorrow to inspect it.

 

[cjist1]

Re: Performance of 1967 5hp johnson question.

Everything in the carb looks fine...though I cant tell if there is a gasket inside the main jet orifice. Maybe thats the problem.

 

[Paul Moir]

Re: Performance of 1967 5hp johnson question.

I'm refering to the gasket that sits over the main nozzle (sorry!) and seals it to the bowl when you put the bowl on the main body of the carb. It's the reddish one in this picture:<br /> http://www.outboard-boat-motor-repa...horse Outboard Boat Motor/images/Evinru50.jpg <br /><br />This is a handy site you might want to use to check your work. The carb in it is a lot older than your's but it's basically the same:<br /> http://www.outboard-boat-motor-repa...hnson 5.5 HP 1954-1964 Carburetor Tune-UP.htm

 

[cjist1]

Re: Performance of 1967 5hp johnson question.

Mine does definately not have that gasket....should it? I need to order a shop manual. I heard the ken cook ones are the way to go.

 

[Paul Moir]

Re: Performance of 1967 5hp johnson question.

Yes it definitely should. Fuel will leak into the main nozzle from the bowl instead of traveling through the metered jet behind the big plug on the front of the bowl. Effectively it makes it a larger jet. It would definitely make the engine run rich at higher speeds. As a temporary test, you can use an o-ring in there. You should feel it crush when you screw the bowl on.<br /><br />I see a bunch of the same manual's Ken Cook has (the factory OEM ones) on ebay right now for very good prices. Don't worry if it's a Johnson or Evinrude manual, they're identical. Use these ebay search terms:<br />(5, 5hp) (Johnson, Evinrude) manual 1967<br />Don't bother with the parts manual. Just look up the '68 5hp at:<br /> http://epc.brp.com/login.aspx?ReturnUrl=/default.aspx?brands=ej&lang=e&brands=ej&lang=e <br />There's no significant differences between '67 or '68.

 

[cjist1]

Re: Performance of 1967 5hp johnson question.

Paul you are the man. Thanks. I made my own little gasket out of a thick rubber inner tube and some hole punches. The motor runs great now. It only pushes the boat a little faster, but the important thing is that it runs correctly now. And it starts on the first pull everytime. Thanks again for everyones help.

 

[Paul Moir]

Re: Performance of 1967 5hp johnson question.

I'm glad to hear you found it. Should help keep the plugs from fowling and save a bit on gas too. Not that a 5hp uses all that much.<br /><br />Happy boating! <br /><br />PS - From the limited amount of playing I've done with inner tube rubber, it seems to swell a lot when submerged in gasoline. That shouldn't be a problem for you but I don't know what the long term effects are. Oh for a sheet of Buna-N!